Seyed Ali Hosseini, Pierre Boivin, Dominique Thévenin, Ilya Karlin. Lattice Boltzmann methods for combustion applications. Progress in Energy and Combustion Science, 2024, 102, pp.101140. ⟨10.1016/j.pecs.2023.101140⟩. ⟨hal-04412786⟩ Plus de détails...
The lattice Boltzmann method, after close to thirty years of presence in computational fluid dynamics has turned into a versatile, efficient and quite popular numerical tool for fluid flow simulations. The lattice Boltzmann method owes its popularity in the past decade to its efficiency, low numerical dissipation and simplicity of its algorithm. Progress in recent years has opened the door for yet another very challenging area of application: Combustion simulations. Combustion is known to be a challenge for numerical tools due to, among many others, the large number of variables and scales both in time and space, leading to a stiff multi-scale problem. In the present work we present a comprehensive overview of models and strategies developed in the past years to model combustion with the lattice Boltzmann method and discuss some of the most recent applications, remaining challenges and prospects.
Seyed Ali Hosseini, Pierre Boivin, Dominique Thévenin, Ilya Karlin. Lattice Boltzmann methods for combustion applications. Progress in Energy and Combustion Science, 2024, 102, pp.101140. ⟨10.1016/j.pecs.2023.101140⟩. ⟨hal-04412786⟩
Journal: Progress in Energy and Combustion Science
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Large eddy simulation of fire-induced flows using Lattice-Boltzmann methods. International Journal of Thermal Sciences, 2024, 197, pp.108801. ⟨10.1016/j.ijthermalsci.2023.108801⟩. ⟨hal-04338538⟩ Plus de détails...
Large-eddy simulations (LES) of the near-field region of large-scale fire plumes are performed for the first time with a pressure-based Lattice Boltzmann method (LBM) with low-Mach number approximation. Two scenarios are considered: the large-scale non-reactive helium plume and the 1 m methane pool fire, both investigated experimentally at Sandia. In the second scenario, a simplified modeling of the combustion and radiation processes is introduced involving a one-step irreversible reaction eddydissipation concept-based combustion model and a radiant fraction model, respectively. In both scenarios, a quantitative agreement is observed with the experimental data and model predictions are consistent with previouslypublished numerical studies. Our simulations demonstrate the computational efficiency of the proposed LBM solver to tackle fire-induced flows, suggesting that LBMs are a good alternative candidate for the modeling of fire-related problems.
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Large eddy simulation of fire-induced flows using Lattice-Boltzmann methods. International Journal of Thermal Sciences, 2024, 197, pp.108801. ⟨10.1016/j.ijthermalsci.2023.108801⟩. ⟨hal-04338538⟩
Journal: International Journal of Thermal Sciences
A safe separation distance (SSD) needs to be considered during firefighting activities (fire suppression or people evacuation) against wildfires. The SSD is of critical interest for both humans and assets located in the wildland-urban interfaces (WUI). In most cases, the safety zone models and guidelines assume a flat terrain and only radiant heating. Nevertheless, injuries or damage do not result exclusively from radiant heating. Indeed, convection must be also considered as a significant contribution of heat transfer, particularly in the presence of the combined effects of sloping terrain and a high wind velocity. In this work, a critical case study is considered for the village of Sari-Solenzara in Corsica (France). This site location was selected by the operational staff since highintensity fire spread is likely to occur in the WUI during wind-blown conditions. This study was carried out for 4 m high shrubland, a sloping terrain of 12° and a wind speed of 16.6 m/s. The numerical simulations were performed using a fully physical fire model, namely, FireStar2D, to investigate a case of fire spreading, which is thought to be representative of most high wildfire risk situations in Corsica. This study is based on the evaluation of the total (radiative and convective) heat flux received by two types of targets (human bodies and buildings) located ahead of the fire front. The results obtained revealed that the radiation was the dominant heat transfer mode in the evaluation of the SSD. In addition, the predictions were consistent with the criterion established by the operational experts, which assumes that in Corsica, a minimum SSD of 50 m is required to keep an equipped firefighter without injury in a fuelbreak named ZAL. This numerical work also provides correlations relating the total heat flux to the SSD.
Jacky Fayad, Gilbert Accary, Frédéric Morandini, François-Joseph Chatelon, Lucile Rossi, et al.. Numerical Assessment of Safe Separation Distance in the Wildland-Urban Interfaces. Fire, 2023, 6 (209), ⟨10.3390/fire6050209⟩. ⟨hal-04101026⟩
G. Farag, P. Boivin, P. Sagaut. Linear interaction approximation for shock/disturbance interaction in a Noble–Abel stiffened gas. Shock Waves, 2023, ⟨10.1007/s00193-023-01131-8⟩. ⟨hal-04097657⟩ Plus de détails...
When departure from the ideal gas equation of state is considered, the Noble-Abel stiffened gas model is an appealing and versatile candidate due to its simple form. The Linear Interaction Approximation formalism is extended to consider non-ideal gas effects introduced by this equation of state. Kovásznay decomposition and adequate definition of the energy of disturbances are provided in the context of this equation of state. Changes with respect to ideal gas are investigated on transfer functions, critical angle and compression factor. Those differences yield concrete effects on the damping and transfer of fluctuations across shock waves. Those changes are further illustrated by considering the interaction of an entropy spot with a Mach 3 stationary shock wave.
G. Farag, P. Boivin, P. Sagaut. Linear interaction approximation for shock/disturbance interaction in a Noble–Abel stiffened gas. Shock Waves, 2023, ⟨10.1007/s00193-023-01131-8⟩. ⟨hal-04097657⟩
Song Zhao, Karthik Bhairapurada, Muhammad Tayyab, Renaud Mercier, Pierre Boivin. Lattice-Boltzmann modelling of the quiet and unstable PRECCINSTA burner modes. Computers and Fluids, 2023, pp.105898. ⟨10.1016/j.compfluid.2023.105898⟩. ⟨hal-04085625⟩ Plus de détails...
Song Zhao, Karthik Bhairapurada, Muhammad Tayyab, Renaud Mercier, Pierre Boivin. Lattice-Boltzmann modelling of the quiet and unstable PRECCINSTA burner modes. Computers and Fluids, 2023, pp.105898. ⟨10.1016/j.compfluid.2023.105898⟩. ⟨hal-04085625⟩
Jacky Fayad, Morandini Frédéric, Gilbert Accary, François-Joseph Chatelon, Clément Wandon, et al.. A Study of Two High Intensity Fires across Corsican Shrubland. Atmosphere, 2023, ⟨10.3390/atmos14030473⟩. ⟨hal-04007587⟩ Plus de détails...
This paper reports two experimental fires conducted at field-scale in Corsica, across a particular mountain shrubland. The orientation of the experimental plots was chosen in such a way that the wind was aligned along the main slope direction in order to obtain a high intensity fire. The first objective was to study the high intensity fire behavior by evaluating the propagation conditions related to its speed and intensity, as well as the geometry of the fire front and its impact on different targets. Therefore, an experimental protocol was designed to determine the properties of the fire spread using UAV cameras and its impact using heat flux gauges. Another objective was to study these experiments numerically using a fully physical fire model, namely FireStar3D. Numerical results concerning the fire dynamics, particularly the ROS, were also compared to other predictions of the FireStar2D model. The comparison with experimental measurements showed the robustness of the 3D approach with a maximum difference of 5.2% for the head fire ROS. The fire intensities obtained revealed that these experiments are representative of high intensity fires, which are very difficult to control in the case of real wildfires. Other parameters investigated numerically (flame geometry and heat fluxes) were also in fairly good agreement with the experimental measurements and confirm the capacity of FireStar3D to predict surface fires of high intensity.
Jacky Fayad, Morandini Frédéric, Gilbert Accary, François-Joseph Chatelon, Clément Wandon, et al.. A Study of Two High Intensity Fires across Corsican Shrubland. Atmosphere, 2023, ⟨10.3390/atmos14030473⟩. ⟨hal-04007587⟩
Benoît Péden, Julien Carmona, Pierre Boivin, Schmitt Thomas, Bénédicte Cuenot, et al.. Numerical assessment of Diffuse-Interface method for air-assisted liquid sheet simulation. Computers and Fluids, 2023, 266, pp.106022. ⟨10.1016/j.compfluid.2023.106022⟩. ⟨hal-04244347⟩ Plus de détails...
This study presents the implementation and validation of a second-order accurate solver for the 4-equation multi-fluid method in a cell-vertex context, to handle aeronautical air-assisted liquid sheet configurations. Validations include one and two-dimensional shock tube problems, Laplace tests, droplets oscillations, and a two-dimensional configuration reminiscent of an aeronautical airblast injector. Promising results are obtained in the last case, especially when the pressure is increased and the characteristic flow times decreased, a trend observed in recent aeronautical developments, but not necessary in classical academical benchmarks. Being fully compatible of the reactive flow formulation of the cell-vertex solver AVBP, this study paves the way to future monolithic simulations of airblast injectors for aeronautical combustion chambers, including both the multi-phase and the reactive regions.
Benoît Péden, Julien Carmona, Pierre Boivin, Schmitt Thomas, Bénédicte Cuenot, et al.. Numerical assessment of Diffuse-Interface method for air-assisted liquid sheet simulation. Computers and Fluids, 2023, 266, pp.106022. ⟨10.1016/j.compfluid.2023.106022⟩. ⟨hal-04244347⟩
S. Taileb, G. Farag, Vincent Robin, A. Chinnayya. A canonical numerical experiment to study detonation initiation from colliding subsonic auto-ignition waves. Physics of Fluids, 2023, 35 (7), pp.076101. ⟨10.1063/5.0156876⟩. ⟨hal-04165459⟩ Plus de détails...
The collision of two subsonic auto-ignition fronts with initial constant velocity was found to transit to detonation only when the collision angle was acute. The interaction of the reactive phase wave with inert hot layers constituted a singularity providing a continuous source of vorticity due to barocline effect. For an acute angle, this singularity that propagated at supersonic speed induced oblique pressure waves, of which resonance, due to the reactivity gradient geometry, near the center of the channel in the fresh gases accelerated the reactive wave fronts until transition to detonation. The numerical results of the present study, even if based on drastic assumptions, were at least in good qualitative consistency with experiments. The geometry of the reactivity gradients can thus provide another seed for the coupling between gas dynamics and heat release. Continuous pressure fluctuations and oblique shocks coming from vorticity sources and sheets from barocline effects can considerably enhance this transition. This path to transition could be complementary to that invoking mixing burning within premixed non-planar turbulent flame brush.
S. Taileb, G. Farag, Vincent Robin, A. Chinnayya. A canonical numerical experiment to study detonation initiation from colliding subsonic auto-ignition waves. Physics of Fluids, 2023, 35 (7), pp.076101. ⟨10.1063/5.0156876⟩. ⟨hal-04165459⟩
Pierre Boivin, Marc Le Boursicaud, Alejandro Millán-Merino, Said Taileb, Josué Melguizo-Gavilanes, et al.. Hydrogen ignition and safety. Efstathios-Al. Tingas. Hydrogen for Future Thermal Engines, Springer International Publishing, pp.161-236, 2023, Green Energy and Technology, 978-3-031-28411-3. ⟨10.1007/978-3-031-28412-0_5⟩. ⟨hal-04244414⟩ Plus de détails...
This chapter provides an overview of H 2 ignition and safety-related questions, to be addressed in the development of future H 2 thermal engines. Basics of H 2 ignition phenomena are covered in the first part, including the well-known branchedchain oxidation reactions described by Semenov & Hinshelwood, as well as useful analytical derivations of induction delay times. The second part provides an overview of classical canonical limit problems, including the explosion-limit (,) diagram, the propagation limits of both deflagrations and detonations, and shock-induced or thermal-induced ignitions. The two remaining parts address two opposite but complementary questions: how to ignite a H 2 engine, and how to prevent hazardous H 2 ignition. In the former, a list of available technologies is offered, while in the latter, simplified models are presented to predict ignition hazards from cold-flow numerical simulations.
Pierre Boivin, Marc Le Boursicaud, Alejandro Millán-Merino, Said Taileb, Josué Melguizo-Gavilanes, et al.. Hydrogen ignition and safety. Efstathios-Al. Tingas. Hydrogen for Future Thermal Engines, Springer International Publishing, pp.161-236, 2023, Green Energy and Technology, 978-3-031-28411-3. ⟨10.1007/978-3-031-28412-0_5⟩. ⟨hal-04244414⟩
Gauthier Wissocq, Said Taileb, Song Zhao, Pierre Boivin. A hybrid lattice Boltzmann method for gaseous detonations. Journal of Computational Physics, 2023, 494, pp.112525. ⟨10.1016/j.jcp.2023.112525⟩. ⟨hal-04244340⟩ Plus de détails...
This article is dedicated to the construction of a robust and accurate numerical scheme based on the lattice Boltzmann method (LBM) for simulations of gaseous detonations. This objective is achieved through careful construction of a fully conservative hybrid lattice Boltzmann scheme tailored for multi-species reactive flows. The core concept is to retain LBM low dissipation properties for acoustic and vortical modes by using the collide and stream algorithm for the particle distribution function, while transporting entropic and species modes via a specifically designed finite-volume scheme. The proposed method is first evaluated on common academic cases, demonstrating its ability to accurately simulate multi-species compressible and reactive flows with discontinuities: the convection of inert species, a Sod shock tube with two ideal gases and a steady one-dimensional inviscid detonation wave. Subsequently, the potential of this novel approach is demonstrated in one- and two-dimensional inviscid unsteady gaseous detonations, highlighting its ability to accurately recover detonation structures and associated instabilities for high activation energies. To the authors' knowledge, this study is the first successful simulation of detonation cellular structures capitalizing on the LBM collide and stream algorithm.
Gauthier Wissocq, Said Taileb, Song Zhao, Pierre Boivin. A hybrid lattice Boltzmann method for gaseous detonations. Journal of Computational Physics, 2023, 494, pp.112525. ⟨10.1016/j.jcp.2023.112525⟩. ⟨hal-04244340⟩
Marc Le Boursicaud, Song Zhao, Jean-Louis Consalvi, Pierre Boivin. An improved passive scalar model for hydrogen hazardous ignition prediction. Combustion and Flame, 2023, 256, pp.112938. ⟨10.1016/j.combustflame.2023.112938⟩. ⟨hal-04169558⟩ Plus de détails...
With an increasing interest in hydrogen as an alternative fuel for transportation, there is a need to develop tools for the prediction of ignition events. A cost-effective passive scalar formulation has been recently developed to predict hydrogen auto-ignition. A single scalar advection-diffusion-reaction equation is used to reproduce the chain-branched ignition process, where the scalar represents the radical pool responsible of ignition (H, O, OH, HO2 , H2O2). The scalar reaction rate is analytically deduced from the Jacobian matrix associated to hydrogen ignition chemistry. This method was found to reproduce with good accuracy the ignition delays obtained by detailed chemistry for temperature where the branching is the leading process. For temperature close or below the crossover temperature, where other phenomenon such as the thermal runaway are important, the scalar approach fails to predict correctly ignition events. Thus, an extension of the scalar source term formulation is proposed to extend its validity over the entire temperature range. In addition, a simple way to approximate the diffusion properties of the scalar is introduced: the radical pool composition may vary drastically, with molecules having very different diffusion properties (e.g. H and HO2). The complete modified framework is presented and its capability is assessed in canonical scenarios and more complex simulations relevant to hydrogen safety.
Marc Le Boursicaud, Song Zhao, Jean-Louis Consalvi, Pierre Boivin. An improved passive scalar model for hydrogen hazardous ignition prediction. Combustion and Flame, 2023, 256, pp.112938. ⟨10.1016/j.combustflame.2023.112938⟩. ⟨hal-04169558⟩
Said Taileb, Alejandro Millán-Merino, Song Zhao, Pierre Boivin. Lattice-Boltzmann modeling of lifted hydrogen jet flames: A new model for hazardous ignition prediction. Combustion and Flame, 2022, 245, pp.112317. ⟨10.1016/j.combustflame.2022.112317⟩. ⟨hal-03796395⟩ Plus de détails...
This numerical study deals with the hazardous ignition of a jet flame in a vitiated co-flow. A novel formulation, based on a passive scalar variable, will be presented to predict hydrogen auto-ignition events. The model, derived from the theoretical analysis of the Jacobian, correctly describes the appearance and absence of auto-ignition in complex configurations based on initial thermodynamic and mixture conditions. No chemical reaction and species equations are required to perform the simulations. Results of Lattice Boltzmann Methods (LBM) simulations of a 3D H 2 /N 2 Cabra flame will be presented using a detailed H 2-Air mechanism. Validation against experimental and numerical results will be provided for the lift-off (distance to auto-ignition). The passive scalar predictions are successfully compared with the reactive simulations. The results show a potential extension of this model to an extensive spectrum of hydrogen safety and large-scale turbulent combustion applications.
Said Taileb, Alejandro Millán-Merino, Song Zhao, Pierre Boivin. Lattice-Boltzmann modeling of lifted hydrogen jet flames: A new model for hazardous ignition prediction. Combustion and Flame, 2022, 245, pp.112317. ⟨10.1016/j.combustflame.2022.112317⟩. ⟨hal-03796395⟩
Alejandro Millán-Merino, Said Taileb, Pierre Boivin. A new method for systematic 1-step chemistry reduction applied to hydrocarbon combustion. Proceedings of the Combustion Institute, 2022, ⟨10.1016/j.proci.2022.08.052⟩. ⟨hal-03825847⟩ Plus de détails...
We propose a new single-step mechanism for the combustion of arbitrary hydrocarbons and alcohols. Unlike most single-step models, no tabulation is required, as the method builds upon a new analytical description of the thermochemical equilibrium of fuel-oxidizer mixtures including dihydrogen and carbon monoxide-two species usually discarded in one-step descriptions-yielding correct adiabatic temperature. The single-step chemistry includes varying stoichiometric coefficients, ensuring a convergence towards thermochemical equilibrium regardless of the local state. The reaction rate is then carefully adjusted to reproduce accurately premixed flames. To tackle ignition simultaneously, an additional passive scalar advection-diffusion-reaction equation is introduced, with a rate fitted on ignition delays. The scalar then serves as an efficiency to modify the single-step reaction rate in autoignition configurations. The obtained scheme is then validated for a wide range of equivalence ratios on homogeneous reactors, premixed flames, a triple flame, and a counterflow diffusion flame. The new analytical thermochemical equilibrium formulation may also serve in speeding up infinitely fast chemistry calculations.
Alejandro Millán-Merino, Said Taileb, Pierre Boivin. A new method for systematic 1-step chemistry reduction applied to hydrocarbon combustion. Proceedings of the Combustion Institute, 2022, ⟨10.1016/j.proci.2022.08.052⟩. ⟨hal-03825847⟩
Pierre Boivin, Yves Connier, Bertrand Dousteyssier, Didier Miallier, Élise Nectoux, et al.. Protohistoire de la moyenne montagne auvergnate : le cas du versant oriental du Cézallier à l’âge du Bronze et au Ier âge du Fer, premier état des lieux. Frédéric Surmely. Archéologie en milieu de montagne dans la région Auvergne-Rhône-Alpes : Actes de la table ronde de Clermont-Ferrand (6 décembre 2019), Presses universitaires Blaise Pascal, pp.137-160, 2022, Terra Mater, 9782383770046. ⟨hal-04123826⟩ Plus de détails...
Pierre Boivin, Yves Connier, Bertrand Dousteyssier, Didier Miallier, Élise Nectoux, et al.. Protohistoire de la moyenne montagne auvergnate : le cas du versant oriental du Cézallier à l’âge du Bronze et au Ier âge du Fer, premier état des lieux. Frédéric Surmely. Archéologie en milieu de montagne dans la région Auvergne-Rhône-Alpes : Actes de la table ronde de Clermont-Ferrand (6 décembre 2019), Presses universitaires Blaise Pascal, pp.137-160, 2022, Terra Mater, 9782383770046. ⟨hal-04123826⟩
Adil Mouahid, Pierre Boivin, Suzanne Diaw, Elisabeth Badens. Widom and extrema lines as criteria for optimizing operating conditions in supercritical processes. Journal of Supercritical Fluids, 2022, 186, pp.105587. ⟨10.1016/j.supflu.2022.105587⟩. ⟨hal-03797377⟩ Plus de détails...
Adil Mouahid, Pierre Boivin, Suzanne Diaw, Elisabeth Badens. Widom and extrema lines as criteria for optimizing operating conditions in supercritical processes. Journal of Supercritical Fluids, 2022, 186, pp.105587. ⟨10.1016/j.supflu.2022.105587⟩. ⟨hal-03797377⟩
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Lattice-Boltzmann modeling of buoyancy-driven turbulent flows. Physics of Fluids, 2022, ⟨10.1063/5.0088409⟩. ⟨hal-03661928⟩ Plus de détails...
The pressure-based hybrid lattice-Boltzmann method presented by Farag & al (Phys. Fluids 2020) is assessed for the simulation of buoyancy driven flows. The model is first validated on Rayleigh-Benard and Rayleigh-Taylor two-dimensional cases. A large-eddy simulation of a turbulent forced plume is then carried out, and results are validated against experiments. A good overall agreement is obtained, both for mean and fluctuations quantities, as well as global entertainment. The self-similarity character of the plume in the far-field is also recovered.
Mostafa Taha, Song Zhao, Aymeric Lamorlette, Jean-Louis Consalvi, Pierre Boivin. Lattice-Boltzmann modeling of buoyancy-driven turbulent flows. Physics of Fluids, 2022, ⟨10.1063/5.0088409⟩. ⟨hal-03661928⟩
Guanxiong Wang, Song Zhao, Pierre Boivin, Eric Serre, Pierre Sagaut. A new hybrid lattice-Boltzmann method for thermal flow simulations in low-Mach number approximation. Physics of Fluids, 2022, 34 (4), pp.046114. ⟨10.1063/5.0091517⟩. ⟨hal-03796386⟩ Plus de détails...
A new low-Mach algorithm for the thermal lattice Boltzmann method (LBM) is proposed aiming at reducing the computational cost of thermal flow simulations in the low Mach number limit. The well-known low Mach number approximation is adopted to accelerate the simulations by enlarging the time step through re-scaling the psuedoacoustic speed to the same order of the fluid motion velocity. This specific process is inspired by the similarity between the artificial compressibility method and the isothermal LBM and is further extended to its thermal counterpart. It must be emphasized that such low-Mach acceleration strategy is in a general form, thus can be easily applied to other compressible LB methods. The present method overcomes the drawback of the classical pressure gradient scaling method due to the pressure gradient changing. The new algorithm is validated by various well-documented academic test cases in laminar [one dimensional gravity column, 2D (two dimensional) rising thermal bubble, and 2D differentially heated square cavity] and turbulent [3D (three dimensional) Taylor–Green vortex and 3D heated cylinder] regimes. All the results show excellent agreement with the reference data and high computational efficiency.
Guanxiong Wang, Song Zhao, Pierre Boivin, Eric Serre, Pierre Sagaut. A new hybrid lattice-Boltzmann method for thermal flow simulations in low-Mach number approximation. Physics of Fluids, 2022, 34 (4), pp.046114. ⟨10.1063/5.0091517⟩. ⟨hal-03796386⟩
Karthik Bhairapurada, Bruno Denet, Pierre Boivin. A Lattice-Boltzmann study of premixed flames thermo-acoustic instabilities. Combustion and Flame, 2022, 240, pp.112049. ⟨hal-03582162⟩ Plus de détails...
We present possibly for the first time Lattice-Boltzmann numerical simulations of thermo-acoustic instabilities of premixed flames. We study flames interacting with an imposed acoustic field where flames submitted to a parametric instability can be observed, as well as plane flames re-stabilized by the acoustic forcing. Self-induced thermo-acoustic oscillations of flames propagating in narrow channels are also studied, indicating an unexpected dependency with the channel width. For both excited and self-excited flames, results confirm that Lattice-Boltzmann method can capture the complex coupling between flame dynamics and acoustics.
Karthik Bhairapurada, Bruno Denet, Pierre Boivin. A Lattice-Boltzmann study of premixed flames thermo-acoustic instabilities. Combustion and Flame, 2022, 240, pp.112049. ⟨hal-03582162⟩
François Joseph Chatelon, Jacques Henri Balbi, Miguel Cruz, Dominique Morvan, Jean Louis Rossi, et al.. Extending the Balbi fire spread Model for field scale conditions: the case of shrubland fires. International Journal of Wildland Fire, 2022, 31 (2), pp.176-192. ⟨10.1071/WF21082⟩. ⟨hal-04064057⟩ Plus de détails...
The 'Balbi model' is a simplified rate of fire spread model aimed at providing fast and accurate simulations for fire spread that can be used by fire managers under operational conditions. This model describes the steady-state spread rate of surface fires by accounting for both radiation and convection heat transfer processes. In the present work the original Balbi model developed for laboratory conditions is improved with changes that address specificities of outdoor fires, such as fuel complexes with a mix of live and dead materials, a larger scale and an open environment. The model is calibrated against a small training dataset (n=25) of shrubland fires conducted in Turkey. A sensitivity analysis of model output is presented and its predictive capacity against a larger independent dataset of experimental fires in shrubland fuels
François Joseph Chatelon, Jacques Henri Balbi, Miguel Cruz, Dominique Morvan, Jean Louis Rossi, et al.. Extending the Balbi fire spread Model for field scale conditions: the case of shrubland fires. International Journal of Wildland Fire, 2022, 31 (2), pp.176-192. ⟨10.1071/WF21082⟩. ⟨hal-04064057⟩
Housseyn Smahi, Djilali Ameur, Joanna Dib, Isabelle Raspo. On the modeling and simulation of coupled adsorption and thermosolutal convection in supercritical carbon dioxide. Journal of Engineering and Applied Science, 2022, 69 (1), pp.5. ⟨10.1186/s44147-021-00054-4⟩. ⟨hal-03567395⟩ Plus de détails...
Abstract In this paper, we present a numerical study along with an exhaustive adsorption investigation in a binary dilute mixture model nearby the solvent’s critical point in a configuration relevant for soil remediation. By means of this model, mass and heat transfer efficiency were qualitatively and quantitatively discussed through this work. The convergence of the solution was evaluated on the values of the Nusselt and Sherwood numbers. The results reveal intense convection expanding into the cavity close to the critical point, thus enabling homogeneous adsorption of the solute. Moreover, the mass fraction perturbation isolines exhibit the existence, along the adsorbent plate, of a thin boundary layer which becomes thinner when approaching the critical point.
Housseyn Smahi, Djilali Ameur, Joanna Dib, Isabelle Raspo. On the modeling and simulation of coupled adsorption and thermosolutal convection in supercritical carbon dioxide. Journal of Engineering and Applied Science, 2022, 69 (1), pp.5. ⟨10.1186/s44147-021-00054-4⟩. ⟨hal-03567395⟩
Journal: Journal of Engineering and Applied Science
Jacky Fayad, Lucile Rossi, Nicolas Frangieh, Carmen Awad, Gilbert Accary, et al.. Numerical study of an experimental high-intensity prescribed fire across Corsican Genista salzmannii vegetation. Fire Safety Journal, 2022, 131, pp.103600. ⟨10.1016/j.firesaf.2022.103600⟩. ⟨hal-04063905⟩ Plus de détails...
This paper reported a high intensity experimental fire conducted during a field-scale experiment on a steep sloped terrain (28°) as part of a winter prescribed burns campaign managed by the local firefighter service in the northwestern region of Corsica. The rate of spread (ROS) of fire, measured using UAV cameras (thermal and visible), was evaluated at 0.45 m/s. The experiment was numerically reproduced using a completely physical 2D model, namely FireStar2D, and the comparison with the experimental measurements mainly concerned the fire ROS and the heat fluxes received by three distant targets placed at the end of the plot. The results analysis shows that the considered fire has a wind-driven regime of propagation with a fire intensity higher than 7 MW/m. The numerical results are in fairly good agreement with the experimental measurements, within 11% difference for the ROS and 5% for the heat fluxes, validating consequently the relevance of the numerical approach to tackle such high-intensity wildfires. Despite the unfavorable wind and humidity conditions for fire propagation (U = 1.67 m/s and RH = 82%), this experiment confirms that such fire can exhibit a dangerous behavior due to the steep slope of the terrain.
Jacky Fayad, Lucile Rossi, Nicolas Frangieh, Carmen Awad, Gilbert Accary, et al.. Numerical study of an experimental high-intensity prescribed fire across Corsican Genista salzmannii vegetation. Fire Safety Journal, 2022, 131, pp.103600. ⟨10.1016/j.firesaf.2022.103600⟩. ⟨hal-04063905⟩
Alejandro Millán-Merino, Said Taileb, Pierre Boivin. A new method for systematic 1-step chemistry reduction applied to hydrocarbon combustion. Proceedings of the Combustion Institute, In press, ⟨10.1016/j.proci.2022.08.052⟩. ⟨hal-04063894⟩ Plus de détails...
We propose a new single-step mechanism for the combustion of arbitrary hydrocarbons and alcohols. Unlike most single-step models, no tabulation is required, as the method builds upon a new analytical description of the thermochemical equilibrium of fuel-oxidizer mixtures including dihydrogen and carbon monoxide-two species usually discarded in one-step descriptions-yielding correct adiabatic temperature. The single-step chemistry includes varying stoichiometric coefficients, ensuring a convergence towards thermochemical equilibrium regardless of the local state. The reaction rate is then carefully adjusted to reproduce accurately premixed flames. To tackle ignition simultaneously, an additional passive scalar advection-diffusion-reaction equation is introduced, with a rate fitted on ignition delays. The scalar then serves as an efficiency to modify the single-step reaction rate in autoignition configurations. The obtained scheme is then validated for a wide range of equivalence ratios on homogeneous reactors, premixed flames, a triple flame, and a counterflow diffusion flame. The new analytical thermochemical equilibrium formulation may also serve in speeding up infinitely fast chemistry calculations.
Alejandro Millán-Merino, Said Taileb, Pierre Boivin. A new method for systematic 1-step chemistry reduction applied to hydrocarbon combustion. Proceedings of the Combustion Institute, In press, ⟨10.1016/j.proci.2022.08.052⟩. ⟨hal-04063894⟩
Guanxiong Wang, Song Zhao, Pierre Boivin, Eric Serre, Pierre Sagaut. A new hybrid Lattice-Boltzmann method for thermal flow simulations in low-Mach number approximation. Physics of Fluids, 2022, Physics of fluids, 34 (046114). ⟨hal-03636905⟩ Plus de détails...
Guanxiong Wang, Song Zhao, Pierre Boivin, Eric Serre, Pierre Sagaut. A new hybrid Lattice-Boltzmann method for thermal flow simulations in low-Mach number approximation. Physics of Fluids, 2022, Physics of fluids, 34 (046114). ⟨hal-03636905⟩
Guillaume Martin, Sébastien Gaime, Pierre Boivin, Bertrand Dousteyssier, Didier Miallier, et al.. Production et diffusion des sarcophages en trachyte de la chaîne des Puys (Massif central, France) au premier Moyen Âge (Ve-IXe s.). Yves Henigfeld; Édith Peytremann. Un monde en mouvement : la circulation des personnes, des biens et des idées à l’époque mérovingienne (Ve-VIIIe siècle), AFAM, pp.241-258, 2022, Mémoires de l’Association française d’Archéologie mérovingienne ; Tome XXXVII, 979-10-90282-02-5. ⟨hal-04128988⟩ Plus de détails...
Guillaume Martin, Sébastien Gaime, Pierre Boivin, Bertrand Dousteyssier, Didier Miallier, et al.. Production et diffusion des sarcophages en trachyte de la chaîne des Puys (Massif central, France) au premier Moyen Âge (Ve-IXe s.). Yves Henigfeld; Édith Peytremann. Un monde en mouvement : la circulation des personnes, des biens et des idées à l’époque mérovingienne (Ve-VIIIe siècle), AFAM, pp.241-258, 2022, Mémoires de l’Association française d’Archéologie mérovingienne ; Tome XXXVII, 979-10-90282-02-5. ⟨hal-04128988⟩
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh. Fifty years of progress in wildland fire modelling: from empirical to fully physical CFD models. Comptes Rendus. Mécanique, 2022, 350 (S1), pp.1-9. ⟨10.5802/crmeca.133⟩. ⟨hal-04063901⟩ Plus de détails...
The aim of this short review is to present the progress made in wildland fire modelling during the last 50 years and the intellectual track followed by wildland fires models, from fully empirical models in the 60s, to semi-empirical ones in the 70s, to fully physical models at the end of the 90s. During the last period, the large diffusion of HPC methods substantially contributed to the development of multiphase formulations applied to wildland fire modelling. Many studies have particularly focused on the effects of various parameters (vegetation, topography, atmosphere) affecting the behaviour of a fire front propagating through a forest fuel layer.
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh. Fifty years of progress in wildland fire modelling: from empirical to fully physical CFD models. Comptes Rendus. Mécanique, 2022, 350 (S1), pp.1-9. ⟨10.5802/crmeca.133⟩. ⟨hal-04063901⟩
Nicolas Godinaud, Pierre Boivin, Pierre Freton, Jean-Jacques Gonzalez, Frédéric Camy-Peyret. Development of a new OpenFOAM solver for plasma cutting modelling. Computers and Fluids, 2022, ⟨10.1016/j.compfluid.2022.105479⟩. ⟨hal-03661919⟩ Plus de détails...
A new OpenFOAM solver is presented, for the simulation of plasma cutting torches. The mathematical model that is introduced is based on the compressible Navier-Stokes equations coupled via source terms to the electric current conservation equation. Due to the conservative and hyperbolic nature of the model, a Godunov-type scheme is used for the first time in the context of plasma cutting simulation. The numerical method consists of a second-order Total Variation Diminishing (TVD) integration with flux Harten-Lax-van Leer-Contact (HLLC) Riemann solver for the flow conservation equations, coupled with a Laplace solver for the current conservation equation. An efficient formulation for the equation of state, accurately taking into account the plasma properties, is also presented. The solver is validated through a set of canonical test cases (shock tubes and 2D Riemann problems) and it is used to simulate a three-dimensional plasma cutting torch. Good agreement is found with the literature, with an improvement in the ability to deal with the shocks occurring during plasma cutting.
Nicolas Godinaud, Pierre Boivin, Pierre Freton, Jean-Jacques Gonzalez, Frédéric Camy-Peyret. Development of a new OpenFOAM solver for plasma cutting modelling. Computers and Fluids, 2022, ⟨10.1016/j.compfluid.2022.105479⟩. ⟨hal-03661919⟩
Gauthier Wissocq, Thomas Coratger, Gabriel Farag, Song Zhao, Pierre Boivin, et al.. Restoring the conservativity of characteristic-based segregated models: application to the hybrid lattice Boltzmann method. Physics of Fluids, 2022, 34 (4), pp.046102. ⟨10.1063/5.0083377⟩. ⟨hal-03627520⟩ Plus de détails...
A general methodology is introduced to build conservative numerical models for fluid simulations based on segregated schemes, where mass, momentum and energy equations are solved by different methods. It is here especially designed for developing new numerical discretizations of the total energy equation, adapted to a thermal coupling with the lattice Boltzmann method (LBM). The proposed methodology is based on a linear equivalence with standard discretizations of the entropy equation, which, as a characteristic variable of the Euler system, allows efficiently decoupling the energy equation with the LBM. To this extent, any LBM scheme is equivalently written under a finite-volume formulation involving fluxes, which are further included in the total energy equation as numerical corrections. The viscous heat production is implicitly considered thanks to the knowledge of the LBM momentum flux. Three models are subsequently derived: a first-order upwind, a Lax-Wendroff and a third-order Godunov-type schemes. They are assessed on standard academic test cases: a Couette flow, entropy spot and vortex convections, a Sod shock tube, several two-dimensional Riemann problems and a shock-vortex interaction. Three key features are then exhibited: 1) the models are conservative by construction, recovering correct jump relations across shock waves, 2) the stability and accuracy of entropy modes can be explicitly controlled, 3) the low dissipation of the LBM for isentropic phenomena is preserved.
Gauthier Wissocq, Thomas Coratger, Gabriel Farag, Song Zhao, Pierre Boivin, et al.. Restoring the conservativity of characteristic-based segregated models: application to the hybrid lattice Boltzmann method. Physics of Fluids, 2022, 34 (4), pp.046102. ⟨10.1063/5.0083377⟩. ⟨hal-03627520⟩
Nicolas Godinaud, Pierre Boivin, Pierre Freton, Jean-Jacques Gonzalez, Frédéric Camy-Peyret. Development of a new OpenFOAM solver for plasma cutting modelling. Computers and Fluids, Elsevier, In press, ⟨10.1016/j.compfluid.2022.105479⟩. ⟨hal-03661919⟩ Plus de détails...
A new OpenFOAM solver is presented, for the simulation of plasma cutting torches. The mathematical model that is introduced is based on the compressible Navier-Stokes equations coupled via source terms to the electric current conservation equation. Due to the conservative and hyperbolic nature of the model, a Godunov-type scheme is used for the first time in the context of plasma cutting simulation. The numerical method consists of a second-order Total Variation Diminishing (TVD) integration with flux Harten-Lax-van Leer-Contact (HLLC) Riemann solver for the flow conservation equations, coupled with a Laplace solver for the current conservation equation. An efficient formulation for the equation of state, accurately taking into account the plasma properties, is also presented. The solver is validated through a set of canonical test cases (shock tubes and 2D Riemann problems) and it is used to simulate a three-dimensional plasma cutting torch. Good agreement is found with the literature, with an improvement in the ability to deal with the shocks occurring during plasma cutting.
Nicolas Godinaud, Pierre Boivin, Pierre Freton, Jean-Jacques Gonzalez, Frédéric Camy-Peyret. Development of a new OpenFOAM solver for plasma cutting modelling. Computers and Fluids, Elsevier, In press, ⟨10.1016/j.compfluid.2022.105479⟩. ⟨hal-03661919⟩
T. Coratger, G. Farag, S. Zhao, Pierre Boivin, P. Sagaut. Large-eddy lattice-Boltzmann modeling of transonic flows. Physics of Fluids, 2021, 33 (11), pp.115112. ⟨10.1063/5.0064944⟩. ⟨hal-03424286⟩ Plus de détails...
T. Coratger, G. Farag, S. Zhao, Pierre Boivin, P. Sagaut. Large-eddy lattice-Boltzmann modeling of transonic flows. Physics of Fluids, 2021, 33 (11), pp.115112. ⟨10.1063/5.0064944⟩. ⟨hal-03424286⟩
Oleksandr Dimitrov, Pierrette Guichardon, Isabelle Raspo, Evelyne Neau. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part II: Modeling Based on the NRTL-PR Model. Industrial and engineering chemistry research, 2021, 60 (30), pp.11513-11524. ⟨10.1021/acs.iecr.1c01545⟩. ⟨hal-03379757⟩ Plus de détails...
Further to the Part I of the present paper, the second Part is concentrated around the VLE modeling of binary mixtures involving the three glycol ethers previously studied experimentally. The authors propose to use the NRTL-PR model for the representation of these non-ideal mixtures. The main difficulties of modelling related to very low vapor pressures and the way of dealing with them are highlighted. The unknown critical parameters for DPM, DPnB and PnB were determined using robust group contribution methods. However, the experimental values of these parameters have never been published before. The main goal of the authors was to obtain the most satisfactory representation of the experimental data provided in the Part I. Some issues that mostly occurred in mixtures involving the PnB as well as in mixtures having very low vapor pressures, were encountered. Nevertheless, we have obtained in general a satisfactory representation of measured points regardless of those issues.
Oleksandr Dimitrov, Pierrette Guichardon, Isabelle Raspo, Evelyne Neau. Vapor–Liquid Equilibria of the Aqueous and Organic Mixtures Composed of Dipropylene Glycol Methyl Ether, Dipropylene Glycol n -Butyl Ether, and Propylene Glycol n -Butyl Ether. Part II: Modeling Based on the NRTL-PR Model. Industrial and engineering chemistry research, 2021, 60 (30), pp.11513-11524. ⟨10.1021/acs.iecr.1c01545⟩. ⟨hal-03379757⟩
Journal: Industrial and engineering chemistry research
Pierre Boivin, M. Tayyab, S. Zhao. Benchmarking a lattice-Boltzmann solver for reactive flows: Is the method worth the effort for combustion?. Physics of Fluids, 2021, 33 (7), pp.071703. ⟨10.1063/5.0057352⟩. ⟨hal-03276189⟩ Plus de détails...
Pierre Boivin, M. Tayyab, S. Zhao. Benchmarking a lattice-Boltzmann solver for reactive flows: Is the method worth the effort for combustion?. Physics of Fluids, 2021, 33 (7), pp.071703. ⟨10.1063/5.0057352⟩. ⟨hal-03276189⟩
Nicolas Frangieh, Gilbert Accary, Jean-Louis Rossi, Dominique Morvan, Sofiane Meradji, et al.. Fuelbreak effectiveness against wind-driven and plume-dominated fires: a 3D numerical study. Fire Safety Journal, 2021, pp.103383. ⟨10.1016/j.firesaf.2021.103383⟩. ⟨hal-03258935⟩ Plus de détails...
The effectiveness of a fuelbreak, created in a homogeneous grassland on a flat terrain, was studied numerically. The analysis relies on 3D numerical simulations that were performed using a detailed physical-fire-model (FIRESTAR3D) based on a multiphase formulation. To avoid border effects, calculations were carried out by imposing periodic boundary conditions along the two lateral sides of the computational domain, reproducing that way a quasi-infinitely long fire front. A total of 72 simulations were carried out for various wind speeds, fuel heights, and fuelbreak widths, which allowed to cover a large spectrum of fire behaviour, ranging from plume-dominated fires to wind-driven fires. The results were classified in three main categories: 1- “Propagation” if fire crossed the fuelbreak with a continuous fire front, 2- “Overshooting” and “Marginal” if fire marginally crosses the fuelbreak with the formation of burning pockets, and 3- “No propagation” if fire does not cross at all the fuelbreak. The ratio of fuelbreak width to fuel height, marking the “Propagation”/“No propagation” transition, was found to be scaled with Byram's convection number Nc as 75.07 × Nc−0.46. The numerical results were also compared to an operational wildfire engineering tool (DIMZAL) dedicated to fuelbreaks dimensioning.
Nicolas Frangieh, Gilbert Accary, Jean-Louis Rossi, Dominique Morvan, Sofiane Meradji, et al.. Fuelbreak effectiveness against wind-driven and plume-dominated fires: a 3D numerical study. Fire Safety Journal, 2021, pp.103383. ⟨10.1016/j.firesaf.2021.103383⟩. ⟨hal-03258935⟩
Nicolas Frangieh, Gilbert Accary, Jean-Louis Rossi, Dominique Morvan, Sofiane Meradji, et al.. Fuelbreak effectiveness against wind-driven and plume-dominated fires: a 3D numerical study. Fire Safety Journal, 2021, pp.103383. ⟨10.1016/j.firesaf.2021.103383⟩. ⟨hal-03597349⟩ Plus de détails...
The effectiveness of a fuelbreak, created in a homogeneous grassland on a flat terrain, was studied numerically. The analysis relies on 3D numerical simulations that were performed using a detailed physical-fire-model (FIRESTAR3D) based on a multiphase formulation. To avoid border effects, calculations were carried out by imposing periodic boundary conditions along the two lateral sides of the computational domain, reproducing that way a quasi-infinitely long fire front. A total of 72 simulations were carried out for various wind speeds, fuel heights, and fuelbreak widths, which allowed to cover a large spectrum of fire behaviour, ranging from plume-dominated fires to wind-driven fires. The results were classified in three main categories: 1- “Propagation” if fire crossed the fuelbreak with a continuous fire front, 2- “Overshooting” and “Marginal” if fire marginally crosses the fuelbreak with the formation of burning pockets, and 3- “No propagation” if fire does not cross at all the fuelbreak. The ratio of fuelbreak width to fuel height, marking the “Propagation”/“No propagation” transition, was found to be scaled with Byram's convection number Nc as 75.07 × Nc−0.46. The numerical results were also compared to an operational wildfire engineering tool (DIMZAL) dedicated to fuelbreaks dimensioning.
Nicolas Frangieh, Gilbert Accary, Jean-Louis Rossi, Dominique Morvan, Sofiane Meradji, et al.. Fuelbreak effectiveness against wind-driven and plume-dominated fires: a 3D numerical study. Fire Safety Journal, 2021, pp.103383. ⟨10.1016/j.firesaf.2021.103383⟩. ⟨hal-03597349⟩
Arnaud Mura, Song Zhao. Turbulence topology evolution in weakly turbulent premixed flames. Physics of Fluids, 2021, 33 (3), pp.035110. ⟨10.1063/5.0039330⟩. ⟨hal-03442314v2⟩ Plus de détails...
In turbulent premixed flames, not only the isotropy of velocity fluctuations is altered by the thermal expansion effect, the dissipative structure of the turbulent flowfield and the flow topology are also deeply influenced by the flame. Considering the joint probability density function (JPDF) of the second and third invariants of the velocity gradient tensor (VGT)-or its traceless counterpart-is a classical way to educe the topology of turbulent flows at these smallest scales. These quantities are analyzed by considering direct numerical simulation databases of premixed flame kernel growth in homogeneous isotropic turbulence (HIT). Two conditions of turbulence-combustion interaction (TCI) are considered, which correspond to two distinct values of the Bray number. The analysis of the VGT shows that the propagating premixed flame and its associated density variations significantly modify the turbulence structure and flow topology. To understand this behavior as the flow interacts with the flame front, Lagrangian dynamics of the VGT and its invariants are studied by considering the conditional mean rate of change vectors. Special emphasis is thus placed on the Lagrangian evolution equations (LEE) of these invariants. To the best of the authors' knowledge, this is first time that such budgets are scrutinized in premixed combustion conditions. The pressure Hessian contribution to the VGT invariants transport equations is shown to be one of the leading-order terms in this evolution, making it critically important to the flow dynamics and turbulence structure.
Arnaud Mura, Song Zhao. Turbulence topology evolution in weakly turbulent premixed flames. Physics of Fluids, 2021, 33 (3), pp.035110. ⟨10.1063/5.0039330⟩. ⟨hal-03442314v2⟩
Carmen Awad, Nicolas Frangieh, Thierry Marcelli, Gilbert Accary, Dominique Morvan, et al.. Numerical study of the moisture content threshold under prescribed burning conditions. Fire Safety Journal, 2021, pp.103324. ⟨10.1016/j.firesaf.2021.103324⟩. ⟨hal-03595964⟩ Plus de détails...
The safety during prescribed burnings could be achieved by conducting these operations under marginal conditions of fire propagation. This type of fire can or cannot propagate on account of small deviations of the burning conditions, mainly the wind speed, the fuel load, and the fuel moisture-content. In this context, numerical simulations of grassland fires were conducted under marginal conditions in order to relate the moisturecontent threshold of propagation success to the wind speed and the fuel load. The simulations were conducted using FireStar2D, a complete physical 2D fire simulator based on a multiphase modelling approach. The 10 mopen wind speed ranged from 0 to 10 m/s and the fuel load varied from 0.1 kg/m 2 to 0.7 kg/m 2. The effects of wind speed and fuel moisture-content on the fire behaviour and on the flame parameters are discussed. The results show that the moisture threshold increases with the fuel load until it reaches a value beyond which there is no dependence. A similar dependence of the moisture threshold on the wind speed is also observed. Finally, empirical formulae were constructed to relate the fuel moisture content threshold to the wind speed and the fuel loading implicitly through Byram's convective number.
Carmen Awad, Nicolas Frangieh, Thierry Marcelli, Gilbert Accary, Dominique Morvan, et al.. Numerical study of the moisture content threshold under prescribed burning conditions. Fire Safety Journal, 2021, pp.103324. ⟨10.1016/j.firesaf.2021.103324⟩. ⟨hal-03595964⟩
G. Farag, S. Zhao, G. Chiavassa, Pierre Boivin. Consistency study of Lattice-Boltzmann schemes macroscopic limit. Physics of Fluids, 2021, 33 (3), pp.037101. ⟨10.1063/5.0039490⟩. ⟨hal-03160898⟩ Plus de détails...
Owing to the lack of consensus about the way Chapman-Enskog should be performed, a new Taylor-Expansion of Lattice-Boltzmann models is proposed. Contrarily to the Chapman-Enskog expansion, recalled in this manuscript, the method only assumes an su ciently small time step. Based on the Taylor expansion, the collision kernel is reinterpreted as a closure for the stress-tensor equation. Numerical coupling of Lattice-Boltzmann models with other numerical schemes, also encompassed by the method, are shown to create error terms whose scalings are more complex than those obtained via Chapman-Enskog. An athermal model and two compressible models are carefully analyzed through this new scope, casting a new light on each model's consistency with the Navier-Stokes equations.
G. Farag, S. Zhao, G. Chiavassa, Pierre Boivin. Consistency study of Lattice-Boltzmann schemes macroscopic limit. Physics of Fluids, 2021, 33 (3), pp.037101. ⟨10.1063/5.0039490⟩. ⟨hal-03160898⟩
Isabelle Cheylan, Song Zhao, Pierre Boivin, Pierre Sagaut. Compressible pressure-based Lattice-Boltzmann applied to humid air with phase change. Applied Thermal Engineering, 2021, pp.116868. ⟨10.1016/j.applthermaleng.2021.116868⟩. ⟨hal-03180596⟩ Plus de détails...
A new compressible pressure-based Lattice Boltzmann Method is proposed to simulate humid air flows with phase change. The variable density and compressible effects are fully resolved, effectively lifting the Boussinesq approximation commonly used, e.g. for meteorological flows. Previous studies indicate that the Boussinesq assumption can lead to errors up to 25%, but the model remains common, for compressible models often suffer from a lack of stability. In order to overcome this issue, a new pressure-based solver is proposed, exhibiting excellent stability properties. Mass and momentum conservation equations are solved by a hybrid recursive regularized Lattice-Boltzmann approach, whereas the enthalpy and species conservation equations are solved using a finite volume method. The solver is based on a pressure-based method coupled with a predictor-corrector algorithm, and incorporates a humid equation of state, as well as a specific boundary condition treatment for phase change. In particular, boundary conditions that handle mass leakage are also proposed and validated. Three test cases are investigated in order to validate this new approach: the Rayleigh-Bénard instability applied to humid air, the atmospheric rising of a condensing moist bubble, and finally the evaporation of a thin liquid film in a vertical channel. Results indicate that the proposed pressure-based Lattice-Boltzmann model is stable and accurate on all cases.
Isabelle Cheylan, Song Zhao, Pierre Boivin, Pierre Sagaut. Compressible pressure-based Lattice-Boltzmann applied to humid air with phase change. Applied Thermal Engineering, 2021, pp.116868. ⟨10.1016/j.applthermaleng.2021.116868⟩. ⟨hal-03180596⟩
M. Tayyab, S. Zhao, Pierre Boivin. Lattice-Boltzmann modeling of a turbulent bluff-body stabilized flame. Physics of Fluids, 2021, 33 (3), pp.031701. ⟨10.1063/5.0038089⟩. ⟨hal-03160901⟩ Plus de détails...
This letter reports the first large eddy simulation of a turbulent flame using a Lattice-Boltzmann model. To that end, simulation of a bluff-body stabilized propane-air flame is carried out, showing an agreement similar to those available in the literature. Computational costs are also reported, indicating that Lattice-Boltzmann modelling of reactive flows is competitive, with around 1000cpuh required to simulate one residence time in the 1,5m burner.
M. Tayyab, S. Zhao, Pierre Boivin. Lattice-Boltzmann modeling of a turbulent bluff-body stabilized flame. Physics of Fluids, 2021, 33 (3), pp.031701. ⟨10.1063/5.0038089⟩. ⟨hal-03160901⟩
T. Lafarge, Pierre Boivin, N. Odier, B. Cuenot. Improved color-gradient method for lattice Boltzmann modeling of two-phase flows. Physics of Fluids, 2021, 33 (8), pp.082110. ⟨10.1063/5.0061638⟩. ⟨hal-03324224⟩ Plus de détails...
This article presents a revised formulation of the color gradient method to model immiscible two-phase flows in the lattice Boltzmann framework. Thanks to this formulation, the color-gradient method is generalized to an arbitrary Equation of State under the form p=f(ρ,ϕ), relieving the nonphysical limitation between density and sound speed ratios present in the original formulation. A fourth-order operator for the equilibrium function is introduced, and its formulation is justified through the calculation of the 3rd order equivalent equation of this numerical scheme. A mathematical development demonstrating how the recoloration phase allows us to solve a conservative Allen–Cahn equation is also proposed. Finally, a novel temporal correction is proposed, improving the numerical stability of the method at high density ratio. Validation tests up to density ratios of 1000 are presented.
T. Lafarge, Pierre Boivin, N. Odier, B. Cuenot. Improved color-gradient method for lattice Boltzmann modeling of two-phase flows. Physics of Fluids, 2021, 33 (8), pp.082110. ⟨10.1063/5.0061638⟩. ⟨hal-03324224⟩
G. Farag, T. Coratger, G. Wissocq, S. Zhao, Pierre Boivin, et al.. A unified hybrid lattice-Boltzmann method for compressible flows: Bridging between pressure-based and density-based methods. Physics of Fluids, 2021, 33 (8), pp.086101. ⟨10.1063/5.0057407⟩. ⟨hal-03324229⟩ Plus de détails...
A unified expression for high-speed compressible segregated consistent lattice Boltzmann methods, namely, pressure-based and improved density-based methods, is given. It is theoretically proved that in the absence of forcing terms, these approaches are strictly identical and can be recast in a unique form. An important result is that the difference with classical density-based methods lies in the addition of fourth-order term in the equilibrium function. It is also shown that forcing terms used to balance numerical errors in both original pressure-based and improved density-based methods can be written in a generalized way. A hybrid segregated efficient lattice-Boltzmann for compressible flow based on this unified model, equipped with a recursive regularization kernel, is proposed and successfully assessed on a wide set of test cases with and without shock waves.
G. Farag, T. Coratger, G. Wissocq, S. Zhao, Pierre Boivin, et al.. A unified hybrid lattice-Boltzmann method for compressible flows: Bridging between pressure-based and density-based methods. Physics of Fluids, 2021, 33 (8), pp.086101. ⟨10.1063/5.0057407⟩. ⟨hal-03324229⟩
S. Zhao, G. Farag, Pierre Boivin, P. Sagaut. Toward fully conservative hybrid lattice Boltzmann methods for compressible flows. Physics of Fluids, 2020, 32 (12), pp.126118. ⟨10.1063/5.0033245⟩. ⟨hal-03087980⟩ Plus de détails...
S. Zhao, G. Farag, Pierre Boivin, P. Sagaut. Toward fully conservative hybrid lattice Boltzmann methods for compressible flows. Physics of Fluids, 2020, 32 (12), pp.126118. ⟨10.1063/5.0033245⟩. ⟨hal-03087980⟩
Kai Zhang, Aymeric Lamorlette. An extensive numerical study of the burning dynamics of wildland fuel using proposed configuration space. International Journal of Heat and Mass Transfer, 2020, 160, pp.120174. ⟨10.1016/j.ijheatmasstransfer.2020.120174⟩. ⟨hal-02960139⟩ Plus de détails...
Physics-based flame models capable of predicting small-scale fire behaviors reduce computational power needed for predicting fires of large- and giga-scale. However, classical model correlations are often developed for 'free fires' without considering vegetation around. These models may result in inaccurate fire modeling due to wrong 'prior' flame shape estimated from theta similar to wind speed. To overcome this defect, three-dimensional small-scale fires with fireline intensity of 100 KW/m are numerically simulated using large eddy simulation. Fire behaviors such as flame tilt angle and heat transfer mechanisms are extensively studied using a newly proposed configuration space {N-C, CdLAI}. The former one represents the ratio between fire to wind power, and the latter one considering the vegetation effect is for the first time introduced in flame models. Using the configuration space, two model correlations for flame tilt angle and radiative heat power reaching the unburnt fuels are proposed. The flame tilt angle theta is directly related to CdLAI (C-d alpha(s)sigma H-s(F)/2), while inversely related to N-C (2gI/ rho 0C(p,0)T(0)U(0)(3)), in contrast to the model proposed for radiative heat power. Comparisons with several classical models evidenced the capability of new flame models in predicting both free and non-free fires. The limits of the validity of the newly proposed models are also discussed.
Kai Zhang, Aymeric Lamorlette. An extensive numerical study of the burning dynamics of wildland fuel using proposed configuration space. International Journal of Heat and Mass Transfer, 2020, 160, pp.120174. ⟨10.1016/j.ijheatmasstransfer.2020.120174⟩. ⟨hal-02960139⟩
Journal: International Journal of Heat and Mass Transfer
Zhen-Hua Jiang, Xi Deng, Feng Xiao, Chao Yan, Jian Yu. A Higher Order Interpolation Scheme of Finite Volume Method for Compressible Flow on Curvilinear Grids. Communications in Computational Physics, 2020, 28 (4), pp.1609-1638. ⟨10.4208/cicp.OA-2019-0091⟩. ⟨hal-02960145⟩ Plus de détails...
A higher order interpolation scheme based on a multi-stage BVD (Boundary Variation Diminishing) algorithm is developed for the FV (Finite Volume) method on non-uniform, curvilinear structured grids to simulate the compressible turbulent flows. The designed scheme utilizes two types of candidate interpolants including a higher order linear-weight polynomial as high as eleven and a THING (Tangent of Hyperbola for INterface Capturing) function with the adaptive steepness. We investigate not only the accuracy but also the efficiency of the methodology through the cost efficiency analysis in comparison with well-designed mapped WENO (Weighted Essentially Non-Oscillatory) scheme. Numerical experimentation including benchmark broadband turbulence problem as well as real-life wall-bounded turbulent flows has been carried out to demonstrate the potential implementation of the present higher order interpolation scheme especially in the ILES (Implicit Large Eddy Simulation) of compressible turbulence.
Zhen-Hua Jiang, Xi Deng, Feng Xiao, Chao Yan, Jian Yu. A Higher Order Interpolation Scheme of Finite Volume Method for Compressible Flow on Curvilinear Grids. Communications in Computational Physics, 2020, 28 (4), pp.1609-1638. ⟨10.4208/cicp.OA-2019-0091⟩. ⟨hal-02960145⟩
Siengdy Tann, Xi Deng, Yuya Shimizu, Raphaël Loubère, Feng Xiao. Solution property preserving reconstruction for finite volume scheme: a boundary variation diminishing+multidimensional optimal order detection framework. International Journal for Numerical Methods in Fluids, 2020, 92 (6), pp.603-634. ⟨10.1002/fld.4798⟩. ⟨hal-02618891⟩ Plus de détails...
G. Farag, S. Zhao, T. Coratger, Pierre Boivin, G. Chiavassa, et al.. A pressure-based regularized lattice-Boltzmann method for the simulation of compressible flows. Physics of Fluids, 2020, 32 (6), pp.066106. ⟨10.1063/5.0011839⟩. ⟨hal-02885427⟩ Plus de détails...
A new pressure-based Lattice-Boltzmann method (HRR-p) is proposed for the simulation of flows for Mach numbers ranging from 0 to 1.5. Compatible with nearest neighbor lattices (e.g. D3Q19), the model consists of a predictor step comparable to classical athermal Lattice-Boltzmann methods, appended with a fully local and explicit correction step for the pressure. Energy conservation-for which the Hermi-tian quadrature is not accurate enough on such lattice-is solved via a classical finite volume MUSCL-Hancock scheme based on the entropy equation. The Euler part of the model is then validated for the transport of three canonical modes (vortex, en-tropy, and acoustic propagation), while its diffusive/viscous properties are assessed via thermal Couette flow simulations. All results match the analytical solutions, with very limited dissipation. Lastly, the robustness of the method is tested in a one dimensional shock tube and a two-dimensional shock-vortex interaction.
G. Farag, S. Zhao, T. Coratger, Pierre Boivin, G. Chiavassa, et al.. A pressure-based regularized lattice-Boltzmann method for the simulation of compressible flows. Physics of Fluids, 2020, 32 (6), pp.066106. ⟨10.1063/5.0011839⟩. ⟨hal-02885427⟩
Xi Deng, Pierre Boivin. Diffuse interface modelling of reactive multi-phase flows applied to a sub-critical cryogenic jet. Applied Mathematical Modelling, 2020, ⟨10.1016/j.apm.2020.04.011⟩. ⟨hal-02561937⟩ Plus de détails...
In order to simulate cryogenic H 2 − O 2 jets under subcritical condition, a numerical model is constructed to solve compressible reactive multi-component flows which involve complex multi-physics processes such as moving material interfaces, shock waves, phase transition and combustion. The liquid and reactive gaseous mixture are described by a homogeneous mixture model with diffusion transport for heat, momentum and species. A hybrid thermodynamic closure strategy is proposed to construct an equation of state (EOS) for the mixture. The phase transition process is modeled by a recent fast relaxation method which gradually reaches the thermo-chemical equilibrium without iterative process. A simplified transport model is also implemented to ensure the accurate behavior in the limit of pure fluids and maintain computational efficiency. Last, a 12-step chemistry model is included to account for hydrogen combustion. Then the developed numerical model is solved with the finite volume method where a low dissipation AUSM (advection upstream splitting method) Riemann solver is extended for multi-component flows. A homogeneous reconstruction strategy compatible with the homogeneous mixture model is adopted to prevent numerical oscillations across material interfaces. Having included these elements, the model is validated on a number of canonical configurations, first for multi-phase flows, and second for reactive flows. These tests allow recovery of the expected behavior in both the multiphase and reactive limits, and the model capability is further demonstrated on a 2D burning cryogenic H 2 − O 2 jet, in a configuration reminiscent of rocket engine ignition.
Xi Deng, Pierre Boivin. Diffuse interface modelling of reactive multi-phase flows applied to a sub-critical cryogenic jet. Applied Mathematical Modelling, 2020, ⟨10.1016/j.apm.2020.04.011⟩. ⟨hal-02561937⟩
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩ Plus de détails...
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, Elsevier, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩ Plus de détails...
Kai Zhang, Salman Verma, Arnaud Trouvé, Aymeric Lamorlette. A study of the canopy effect on fire regime transition using an objectively defined Byram convective number. Fire Safety Journal, Elsevier, 2020, 112, pp.102950. ⟨10.1016/j.firesaf.2020.102950⟩. ⟨hal-02469260⟩
Xi Deng, Yuya Shimizu, Bin Xie, Feng Xiao. Constructing higher order discontinuity-capturing schemes with upwind-biased interpolations and boundary variation diminishing algorithm. Computers and Fluids, 2020, 200, pp.104433. ⟨10.1016/j.compfluid.2020.104433⟩. ⟨hal-02892513⟩ Plus de détails...
Based on the fifth-order scheme in our previous work (Deng et. al (2019) [28]), a new framework of constructing very high order discontinuity-capturing schemes is proposed for finite volume method. These schemes, so-called PnTm - BVD (polynomial of n-degree and THINC function of m-level reconstruction based on BVD algorithm), are designed by employing high-order upwind-biased interpolations and THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive steepness as the reconstruction candidates. The final reconstruction function in each cell is determined with a multi-stage BVD (Boundary Variation Diminishing) algorithm so as to effectively control numerical oscillation and dissipation. We devise the new schemes up to eleventh order in an efficient way by directly increasing the order of the underlying upwind scheme using high order polynomials. The analysis of the spectral property and accuracy tests show that the new reconstruction strategy well preserves the low-dissipation property of the underlying upwind schemes with high-order polynomials for smooth solution over all wave numbers and realizes n + 1 order convergence rate. The performance of new schemes is examined through widely used benchmark tests, which demonstrate that the proposed schemes are capable of simultaneously resolving small-scale flow features with high resolution and capturing discontinuities with low dissipation. With outperforming results and simplicity in algorithm, the new reconstruction strategy shows great potential as an alternative numerical framework for computing nonlinear hyperbolic conservation laws that have discontinuous and smooth solutions of different scales.
Xi Deng, Yuya Shimizu, Bin Xie, Feng Xiao. Constructing higher order discontinuity-capturing schemes with upwind-biased interpolations and boundary variation diminishing algorithm. Computers and Fluids, 2020, 200, pp.104433. ⟨10.1016/j.compfluid.2020.104433⟩. ⟨hal-02892513⟩
Xi Deng, Yuya Shimizu, Bin Xie, Feng Xiao. Constructing higher order discontinuity-capturing schemes with upwind-biased interpolations and boundary variation diminishing algorithm. Computers and Fluids, Elsevier, 2020, 200, pp.104433. ⟨10.1016/j.compfluid.2020.104433⟩. ⟨hal-02892513⟩ Plus de détails...
Based on the fifth-order scheme in our previous work (Deng et. al (2019) [28]), a new framework of constructing very high order discontinuity-capturing schemes is proposed for finite volume method. These schemes, so-called PnTm - BVD (polynomial of n-degree and THINC function of m-level reconstruction based on BVD algorithm), are designed by employing high-order upwind-biased interpolations and THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive steepness as the reconstruction candidates. The final reconstruction function in each cell is determined with a multi-stage BVD (Boundary Variation Diminishing) algorithm so as to effectively control numerical oscillation and dissipation. We devise the new schemes up to eleventh order in an efficient way by directly increasing the order of the underlying upwind scheme using high order polynomials. The analysis of the spectral property and accuracy tests show that the new reconstruction strategy well preserves the low-dissipation property of the underlying upwind schemes with high-order polynomials for smooth solution over all wave numbers and realizes n + 1 order convergence rate. The performance of new schemes is examined through widely used benchmark tests, which demonstrate that the proposed schemes are capable of simultaneously resolving small-scale flow features with high resolution and capturing discontinuities with low dissipation. With outperforming results and simplicity in algorithm, the new reconstruction strategy shows great potential as an alternative numerical framework for computing nonlinear hyperbolic conservation laws that have discontinuous and smooth solutions of different scales.
Xi Deng, Yuya Shimizu, Bin Xie, Feng Xiao. Constructing higher order discontinuity-capturing schemes with upwind-biased interpolations and boundary variation diminishing algorithm. Computers and Fluids, Elsevier, 2020, 200, pp.104433. ⟨10.1016/j.compfluid.2020.104433⟩. ⟨hal-02892513⟩
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, 2020, 506, pp.112371. ⟨10.1016/j.fluid.2019.112371⟩. ⟨hal-02325903⟩ Plus de détails...
Relative permittivity, also known as static dielectric constant, is a key property of solvents in electrolyte solutions. It strongly influences the solubility of solutes and, therefore, it can be used as a predictive tool in chemical engineering processes. Relative permittivity also plays an essential role in the modeling of phase equilibria of electrolyte systems, since it is involved in the Debye-Hückel model and in the Mean Spherical Approximation, commonly used to represent long-range interactions between ions. In this paper, we propose a new temperature-dependent correlation for the relative permittivity of liquid water, methanol and ethanol, valid in a wide temperature range, including very high temperatures. Comparison with other literature equations evidenced that the main interest of the proposed correlation is to allow satisfactory predictions of the relative permittivity, not only in the range of validity of other literature models, but also in the high temperature domain, including supercritical temperatures for water. The new correlation is then used with the NRTL-PRA EoS to predict vapor pressure of water with several salts, including single electrolytes and two-salts mixtures; it must be noted that the modeling presented in this work is relevant for any GE/EoS model, since in this case (binary interactions between water and ions being equal to zero), the excess Gibbs energy reduces to the Long-Range term derived from the Pitzer-Debye-Hückel model. A temperature-dependent correction of the solvent relative permittivity is proposed to account for its dependence on ion mole fraction in this Long-Range term. Results thus obtained show that this correction leads to an accurate prediction both: for vapor pressures of aqueous electrolyte solutions in a very wide temperature domain and for the modeling of vapor-liquid equilibria of methanol-water and ethanol-water mixtures with several salts.
Isabelle Raspo, Evelyne Neau. An empirical correlation for the relative permittivity of liquids in a wide temperature range: application to the modeling of electrolyte systems with a GE/EoS approach.. Fluid Phase Equilibria, 2020, 506, pp.112371. ⟨10.1016/j.fluid.2019.112371⟩. ⟨hal-02325903⟩
M. Tayyab, S. Zhao, Y. Feng, Pierre Boivin. Hybrid regularized Lattice-Boltzmann modelling of premixed and non-premixed combustion processes. Combustion and Flame, 2020, 211, pp.173-184. ⟨10.1016/j.combustflame.2019.09.029⟩. ⟨hal-02346556⟩ Plus de détails...
A Lattice-Boltzmann model for low-Mach reactive flows is presented, built upon our recently published model (Comb & Flame, 196, 2018). The approach is hybrid and couples a Lattice-Boltzmann solver for the resolution of mass and momentum conservation and a finite difference solver for the energy and species conservation. Having lifted the constant thermodynamic and transport properties assumptions, the model presented now fully accounts for the classical reactive flow thermodynamic closure: each component is assigned NASA coefficients for calculating its thermodynamic properties. A temperature-dependent viscosity is considered, from which are deduced thermo-diffusive properties via specification of Prandtl and component-specific Schmidt numbers. Another major improvement from our previous contribution is the derivation of an advanced collision kernel compatible of multi-component reactive flows stable in high shear flows. Validation is carried out first on premixed configurations, through simulation of the planar freely propagating flame, the growth of the associated Darrieus-Landau instability and three regimes of flame-vortex interaction. A double shear layer test case including a flow-stabilized diffusion flame is then presented and results are compared with DNS simulations, showing excellent agreement.
M. Tayyab, S. Zhao, Y. Feng, Pierre Boivin. Hybrid regularized Lattice-Boltzmann modelling of premixed and non-premixed combustion processes. Combustion and Flame, 2020, 211, pp.173-184. ⟨10.1016/j.combustflame.2019.09.029⟩. ⟨hal-02346556⟩
Jacques Henri Balbi, François Joseph Chatelon, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli, et al.. A convective–radiative propagation model for wildland fires. International Journal of Wildland Fire, 2020, ⟨10.1071/WF19103⟩. ⟨hal-02570863⟩ Plus de détails...
Jacques Henri Balbi, François Joseph Chatelon, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli, et al.. A convective–radiative propagation model for wildland fires. International Journal of Wildland Fire, 2020, ⟨10.1071/WF19103⟩. ⟨hal-02570863⟩
Gilbert Accary, Duncan Sutherland, Nicolas Frangieh, Khalid Moinuddin, Ibrahim Shamseddine, et al.. Physics-Based Simulations of Flow and Fire Development Downstream of a Canopy. Atmosphere, 2020, 11 (7), pp.683. ⟨10.3390/atmos11070683⟩. ⟨hal-02957445⟩ Plus de détails...
The behavior of a grassland fire propagating downstream of a forest canopy has been simulated numerically using the fully physics-based wildfire model FIRESTAR3D. This configuration reproduces quite accurately the situation encountered when a wildfire spreads from a forest to an open grassland, as can be the case in a fuel break or a clearing, or during a prescribed burning operation. One of the objectives of this study was to evaluate the impact of the presence of a canopy upstream of a grassfire, especially the modifications of the local wind conditions before and inside a clearing or a fuel break. The knowledge of this kind of information constitutes a major element in improving the safety conditions of forest managers and firefighters in charge of firefighting or prescribed burning operations in such configurations. Another objective was to study the behavior of the fire under realistic turbulent flow conditions, i.e., flow resulting from the interaction between an atmospheric boundary layer (ABL) with a surrounding canopy. Therefore, the study was divided into two phases. The first phase consisted of generating an ABL/canopy turbulent flow above a pine forest (10 m high, 200 m long) using periodic boundary conditions along the streamwise direction. Large Eddy Simulations (LES) were carried out for a sufficiently long time to achieve a quasi-fully developed turbulence. The second phase consisted of simulating the propagation of a surface fire through a grassland, bordered upstream by a forest section (having the same characteristics used for the first step), while imposing the turbulent flow obtained from the first step as a dynamic inlet condition to the domain. The simulations were carried out for a wind speed that ranged between 1 and 12 m/s; these values have allowed the simulations to cover the two regimes of propagation of surfaces fires, namely plume-dominated and wind-driven fires.
Gilbert Accary, Duncan Sutherland, Nicolas Frangieh, Khalid Moinuddin, Ibrahim Shamseddine, et al.. Physics-Based Simulations of Flow and Fire Development Downstream of a Canopy. Atmosphere, 2020, 11 (7), pp.683. ⟨10.3390/atmos11070683⟩. ⟨hal-02957445⟩
Kai Zhang, Aymeric Lamorlette. An extensive numerical study of the burning dynamics of wildland fuel using proposed configuration space. International Journal of Heat and Mass Transfer, 2020, 160, pp.120174. ⟨10.1016/j.ijheatmasstransfer.2020.120174⟩. ⟨hal-03232086⟩ Plus de détails...
Physics-based flame models capable of predicting small-scale fire behaviors reduce computational power needed for predicting fires of large- and giga-scale. However, classical model correlations are often developed for 'free fires' without considering vegetation around. These models may result in inaccurate fire modeling due to wrong 'prior' flame shape estimated from theta similar to wind speed. To overcome this defect, three-dimensional small-scale fires with fireline intensity of 100 KW/m are numerically simulated using large eddy simulation. Fire behaviors such as flame tilt angle and heat transfer mechanisms are extensively studied using a newly proposed configuration space {N-C, CdLAI}. The former one represents the ratio between fire to wind power, and the latter one considering the vegetation effect is for the first time introduced in flame models. Using the configuration space, two model correlations for flame tilt angle and radiative heat power reaching the unburnt fuels are proposed. The flame tilt angle theta is directly related to CdLAI (C-d alpha(s)sigma H-s(F)/2), while inversely related to N-C (2gI/ rho 0C(p,0)T(0)U(0)(3)), in contrast to the model proposed for radiative heat power. Comparisons with several classical models evidenced the capability of new flame models in predicting both free and non-free fires. The limits of the validity of the newly proposed models are also discussed.
Kai Zhang, Aymeric Lamorlette. An extensive numerical study of the burning dynamics of wildland fuel using proposed configuration space. International Journal of Heat and Mass Transfer, 2020, 160, pp.120174. ⟨10.1016/j.ijheatmasstransfer.2020.120174⟩. ⟨hal-03232086⟩
Journal: International Journal of Heat and Mass Transfer
Nicolas Frangieh, Gilbert Accary, Dominique Morvan, Sofiane Meradji, Oleg Bessonov. Wildfires front dynamics: 3D structures and intensity at small and large scales. Combustion and Flame, 2020, 211, pp.54-67. ⟨10.1016/j.combustflame.2019.09.017⟩. ⟨hal-02892557⟩ Plus de détails...
The 3D structure of a fire front propagating through a homogeneous porous solid-fuel layer was studied numerically at laboratory and field scales. At laboratory scale, wind-tunnel fires propagating through laser-cut cardboard fuel were numerically reproduced, while at field scale, simulations of grassland fires with quasi-infinite fire front were carried out for different wind speeds. These simulations were performed using FIRESTAR3D, based on a multiphase formulation that includes the main physical phenomena governing fire behavior. An unsteady RANS approach and a Large Eddy Simulation (LES) approach were used to simulate the reactive turbulent flow, whereas turbulent combustion was modeled using Eddy Dissipation Concept (EDC). Unlike other 3D wildfire tools available in the community, such as FIRETEC and WFDS, the model is based on an implicit, low-Mach number resolution of the governing equations, and makes no empirical assumptions in the resolution of the radiative transfer equation. The comparison with the experimental data concerned mainly the Rate of Spread (ROS) of fire, the fireline intensity, the flame-zone depth, and the wavelength characterizing the crest-and-trough structure of the fire front along the transverse direction. Particular attention was drawn to the similitude in the fire front dynamics between small and large scales. In order to highlight the physical mechanisms responsible for this dynamics, a dimensional analysis was carried out by introducing Byram's convection number N-C based on the fireline intensity and Froude's numbers Fr based on the characteristic wavelength of the fire-front structure. The analysis shows that all the results (wind-tunnel fires and grassland fires, experimental and numerical) collapsed on a single scaling law in the form Fr = N-C(-)2/3.
Nicolas Frangieh, Gilbert Accary, Dominique Morvan, Sofiane Meradji, Oleg Bessonov. Wildfires front dynamics: 3D structures and intensity at small and large scales. Combustion and Flame, 2020, 211, pp.54-67. ⟨10.1016/j.combustflame.2019.09.017⟩. ⟨hal-02892557⟩
Nicolas Frangieh, Gilbert Accary, Dominique Morvan, Sofiane Meradji, Oleg Bessonov. Wildfires front dynamics: 3D structures and intensity at small and large scales. Combustion and Flame, Elsevier, 2020, 211, pp.54-67. ⟨10.1016/j.combustflame.2019.09.017⟩. ⟨hal-02892557⟩ Plus de détails...
The 3D structure of a fire front propagating through a homogeneous porous solid-fuel layer was studied numerically at laboratory and field scales. At laboratory scale, wind-tunnel fires propagating through laser-cut cardboard fuel were numerically reproduced, while at field scale, simulations of grassland fires with quasi-infinite fire front were carried out for different wind speeds. These simulations were performed using FIRESTAR3D, based on a multiphase formulation that includes the main physical phenomena governing fire behavior. An unsteady RANS approach and a Large Eddy Simulation (LES) approach were used to simulate the reactive turbulent flow, whereas turbulent combustion was modeled using Eddy Dissipation Concept (EDC). Unlike other 3D wildfire tools available in the community, such as FIRETEC and WFDS, the model is based on an implicit, low-Mach number resolution of the governing equations, and makes no empirical assumptions in the resolution of the radiative transfer equation. The comparison with the experimental data concerned mainly the Rate of Spread (ROS) of fire, the fireline intensity, the flame-zone depth, and the wavelength characterizing the crest-and-trough structure of the fire front along the transverse direction. Particular attention was drawn to the similitude in the fire front dynamics between small and large scales. In order to highlight the physical mechanisms responsible for this dynamics, a dimensional analysis was carried out by introducing Byram's convection number N-C based on the fireline intensity and Froude's numbers Fr based on the characteristic wavelength of the fire-front structure. The analysis shows that all the results (wind-tunnel fires and grassland fires, experimental and numerical) collapsed on a single scaling law in the form Fr = N-C(-)2/3.
Nicolas Frangieh, Gilbert Accary, Dominique Morvan, Sofiane Meradji, Oleg Bessonov. Wildfires front dynamics: 3D structures and intensity at small and large scales. Combustion and Flame, Elsevier, 2020, 211, pp.54-67. ⟨10.1016/j.combustflame.2019.09.017⟩. ⟨hal-02892557⟩
Muhammad Tayyab, Basile Radisson, Christophe Almarcha, B. Denet, Pierre Boivin. Experimental and numerical Lattice-Boltzmann investigation of the Darrieus-Landau instability. Combustion and Flame, 2020, 221, pp.103-109. ⟨10.1016/j.combustflame.2020.07.030⟩. ⟨hal-02921517⟩ Plus de détails...
We present an experimental and numerical investigation of the Darrieus- Landau instability in a quasi two-dimensional Hele-Shaw cell. Experiments and Lattice-Boltzmann numerical simulations are compared with Darrieus- Landau analytical theory, showing an excellent agreement for the exponential growth rate of the instability in the linear regime. The negative growth rate – second solution of the dispersion relation – was also measured numerically for the first time to the authors’ knowledge. Experiments and numerical simulations were then carried out beyond the cutoff wavelength, providing good agreement even in the unexplored regime where Darrieus-Landau is supplanted by diffusive stabilization. Lastly, the non-linear evolution involving the merging of crests on the experimental flame front is also successfully recovered using both the Michelson-Sivashinsky equation integration and the Lattice-Boltzmann simulation.
Muhammad Tayyab, Basile Radisson, Christophe Almarcha, B. Denet, Pierre Boivin. Experimental and numerical Lattice-Boltzmann investigation of the Darrieus-Landau instability. Combustion and Flame, 2020, 221, pp.103-109. ⟨10.1016/j.combustflame.2020.07.030⟩. ⟨hal-02921517⟩
Erwan Deriaz, Pierre Haldenwang. Non-linear CFL Conditions Issued from the von Neumann Stability Analysis for the Transport Equation. Journal of Scientific Computing, 2020, 85 (1), pp.5. ⟨10.1007/s10915-020-01302-0⟩. ⟨hal-03231866⟩ Plus de détails...
This paper presents a theory of the possible non-linear stability conditions encountered in the simulation of convection dominated problems. Its main objective is to study and justify original CFL-like stability conditions thanks to the von Neumann stability analysis. In particular, we exhibit a wide variety of stability conditions of the type t ≤ C x α with t the time step, x the space step, and α a rational number within the interval [1, 2]. Numerical experiments corroborate these theoretical results.
Erwan Deriaz, Pierre Haldenwang. Non-linear CFL Conditions Issued from the von Neumann Stability Analysis for the Transport Equation. Journal of Scientific Computing, 2020, 85 (1), pp.5. ⟨10.1007/s10915-020-01302-0⟩. ⟨hal-03231866⟩
Jacques Henri Balbi, François Joseph Chatelon, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli, et al.. A convective–radiative propagation model for wildland fires. International Journal of Wildland Fire, 2020, ⟨10.1071/WF19103⟩. ⟨hal-03251626⟩ Plus de détails...
The 'Balbi model' is a simplified steady-state physical propagation model for surface fires that considers radiative heat transfer from the surface area of burning fuel particles as well as from the flame body. In this work, a completely new version of this propagation model for wildand fires is proposed. Even if, in the present work, this model is confined to laboratory experiments, its purpose is to be used at a larger scale in the field under operational conditions. This model was constructed from a radiative propagation model with the addition of a convective heat transfer term resulting from the impingement of packets of hot reacting gases on unburnt fuel elements located at the base of the flame. The flame inside the fuel bed is seen as the 'fingers of fire' described in the literature. The proposed model is physics-based, faster than real time and fully predictive, which means that model parameters do not change from one experiment to another. The predicted rate of spread is applied to a large set of laboratory experiments (through homogeneous pine needles and excelsior fuel beds) and is compared with the predictions of both a very simple empirical model (Catchpole) and a detailed physical model (FireStar2D).
Jacques Henri Balbi, François Joseph Chatelon, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli, et al.. A convective–radiative propagation model for wildland fires. International Journal of Wildland Fire, 2020, ⟨10.1071/WF19103⟩. ⟨hal-03251626⟩
Implicit large eddy simulation (ILES) of compressible turbulence with shock capturing schemes requires wide investigations and numerical experiments. In this study, a newly proposed PnTm - BVD (polynomial of n-degree and THINC function of m-level reconstruction based on BVD algorithm) shock capturing scheme is introduced to simulate compressible turbulence flow with ILES. The new scheme is designed by employing high-order linear-weight polynomials and THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive steepness as the reconstruction candidates. The final reconstruction function in each cell is determined with a multi-stage BVD (Boundary Variation Diminishing) algorithm so as to effectively control numerical oscillation and dissipation. Numerical tests involving shock waves and broadband turbulence are conducted in comparison with WENO (Weighted Essentially Non-oscillatory) schemes which are widely used in ILES. The results demonstrate performing ILES with PnTm- BVD scheme is able to obtain higher resolution and more faithful results than WENO does. Importantly, the superiority of PnTm-BVD becomes more notable in high wave-number region. Thus this paper provides and verifies a new scheme which is promising in providing high-resolution results for real-case ILES of compressible turbulence flow.
Xi Deng, Zhen-Hua Jiang, Feng Xiao, Chao Yan. Implicit large eddy simulation of compressible turbulence flow with PnTm − BVD scheme. Applied Mathematical Modelling, 2020, 77, pp.17-31. ⟨10.1016/j.apm.2019.07.022⟩. ⟨hal-03235122⟩
Implicit large eddy simulation (ILES) of compressible turbulence with shock capturing schemes requires wide investigations and numerical experiments. In this study, a newly proposed PnTm - BVD (polynomial of n-degree and THINC function of m-level reconstruction based on BVD algorithm) shock capturing scheme is introduced to simulate compressible turbulence flow with ILES. The new scheme is designed by employing high-order linear-weight polynomials and THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive steepness as the reconstruction candidates. The final reconstruction function in each cell is determined with a multi-stage BVD (Boundary Variation Diminishing) algorithm so as to effectively control numerical oscillation and dissipation. Numerical tests involving shock waves and broadband turbulence are conducted in comparison with WENO (Weighted Essentially Non-oscillatory) schemes which are widely used in ILES. The results demonstrate performing ILES with PnTm- BVD scheme is able to obtain higher resolution and more faithful results than WENO does. Importantly, the superiority of PnTm-BVD becomes more notable in high wave-number region. Thus this paper provides and verifies a new scheme which is promising in providing high-resolution results for real-case ILES of compressible turbulence flow.
Xi Deng, Zhen-Hua Jiang, Feng Xiao, Chao Yan. Implicit large eddy simulation of compressible turbulence flow with PnTm − BVD scheme. Applied Mathematical Modelling, 2020, 77, pp.17-31. ⟨10.1016/j.apm.2019.07.022⟩. ⟨hal-02892550⟩
Dan Feng, Laure Malleret, Guillaume Chiavassa, Olivier Boutin, Audrey Soric. Biodegradation capabilities of acclimated activated sludge towards glyphosate: Experimental study and kinetic modeling. Biochemical Engineering Journal, 2020, 161, pp.107643. ⟨10.1016/j.bej.2020.107643⟩. ⟨hal-02960167⟩ Plus de détails...
The acclimation process of activated sludge from a wastewater treatment plant for degradation of glyphosate and its biodegradation kinetics were studied in a batch reactor. The parameters monitored included the concentrations of glyphosate, as well as aminomethylphosphonic acid (AMPA), its main metabolite, total organic carbon (TOC), pH, dissolved oxygen (DO) and biomass concentration. M the end of the acclimation process, glyphosate removal efficiency of the acclimated sludge was compared to the fresh sludge one. The results showed that the acclimation process highly increased degradation efficiency. Complete glyphosate removal has been achieved during kinetics experiments. Glyphosate removal kinetic of the acclimated sludge was modeled by Monod model that accurately fitted the experimental results with a maximum growth rate (mu(max)) of 0.34 h(-1) and half-saturation constant (K-s) of 1600 mg L-1. Finally, a biodegradation pathway of glyphosate used as carbon source was proposed.
Dan Feng, Laure Malleret, Guillaume Chiavassa, Olivier Boutin, Audrey Soric. Biodegradation capabilities of acclimated activated sludge towards glyphosate: Experimental study and kinetic modeling. Biochemical Engineering Journal, 2020, 161, pp.107643. ⟨10.1016/j.bej.2020.107643⟩. ⟨hal-02960167⟩
Erwan Deriaz, Pierre Haldenwang. Non-linear CFL Conditions Issued from the von Neumann Stability Analysis for the Transport Equation. Journal of Scientific Computing, 2020, 85 (1), pp.5. ⟨10.1007/s10915-020-01302-0⟩. ⟨hal-03231866⟩ Plus de détails...
This paper presents a theory of the possible non-linear stability conditions encountered in the simulation of convection dominated problems. Its main objective is to study and justify original CFL-like stability conditions thanks to the von Neumann stability analysis. In particular, we exhibit a wide variety of stability conditions of the type t ≤ C x α with t the time step, x the space step, and α a rational number within the interval [1, 2]. Numerical experiments corroborate these theoretical results.
Erwan Deriaz, Pierre Haldenwang. Non-linear CFL Conditions Issued from the von Neumann Stability Analysis for the Transport Equation. Journal of Scientific Computing, 2020, 85 (1), pp.5. ⟨10.1007/s10915-020-01302-0⟩. ⟨hal-03231866⟩
Bin Xie, Xi Deng, Shijun Liao. High-fidelity solver on polyhedral unstructured grids for low-Mach number compressible viscous flow. Computer Methods in Applied Mechanics and Engineering, 2019, 357, pp.112584. ⟨10.1016/j.cma.2019.112584⟩. ⟨hal-02467981⟩ Plus de détails...
In this article, we developed an unstructured fluid solver based on finite volume framework for the low-Mach number compressible flows. The present method, so-called FVMS3 (Finite Volume method based on Merged Stencil with 3rd-order reconstruction) formulates two different numerical procedures for spatial reconstructions based on the quadratic polynomial which is performed by using least-square approximations on a merged stencil. In order to improve the reconstruction for discontinuities, we propose the limiting projection approach and smoothness adaptive fitting (SAF) scheme to suppress the numerical oscillation and limit the numerical dissipation. The resulting discretization algorithm that combines FVMS3 with SAF-based limiting projection scheme has third-order accuracy and resolves both smooth and non-smooth solutions with excellent quality. Additionally, a novel numerical model has been proposed by introducing the advection upstream splitting method (AUSM) flux into the pressure projection formulation which results in a unified scheme that works uniformly up to the incompressible limit. The fluid solver that integrates all above new efforts provides high-fidelity solutions for compressible viscous flows particularly for the low Mach regime. The performance of this new solver is verified by numerous benchmark tests. Our numerical results show that the proposed scheme gives accurate and robust solutions for a wide spectrum of test problems.
Bin Xie, Xi Deng, Shijun Liao. High-fidelity solver on polyhedral unstructured grids for low-Mach number compressible viscous flow. Computer Methods in Applied Mechanics and Engineering, 2019, 357, pp.112584. ⟨10.1016/j.cma.2019.112584⟩. ⟨hal-02467981⟩
Journal: Computer Methods in Applied Mechanics and Engineering
Siengdy Tann, Xi Deng, Yuya Shimizu, Raphaël Loubère, Feng Xiao. Solution Property Preserving Reconstruction for Finite Volume Scheme: a BVD+MOOD framework. International Journal for Numerical Methods in Fluids, In press, ⟨10.1002/fld.4798⟩. ⟨hal-02397156⟩ Plus de détails...
The purpose of this work is to build a general framework to reconstruct the underlying fields within a Finite Volume (FV) scheme solving a hyperbolic system of PDEs (Partial Differential Equations). In an FV context, the data are piece-wise constants per computational cell and the physical fields are reconstructed taking into account neighbor cell values. These reconstructions are further used to evaluate the physical states usually used to feed a Riemann solver which computes the associated numerical fluxes. The physical field reconstructions must obey some properties linked to the system of PDEs such as the positivity, but also some numerically based ones, like an essentially non-oscillatory behaviour. Moreover, the reconstructions should be high accurate for smooth flows and robust/stable for discontinuous solutions. To ensure a Solution Property Preserving Reconstruction, we introduce a methodology to blend high/low order polynomials and hyperbolic tangent reconstructions. A Boundary Variation Diminishing (BVD) algorithm is employed to select the best reconstruction in each cell. An a posteriori MOOD detection procedure is employed to ensure the positivity by re-computing the rare problematic cells using a robust first-order FV scheme. We illustrate the performance of the proposed scheme via the numerical simulations for some benchmark tests which involve vacuum or near vacuum states, strong discontinuities and also smooth flows. The proposed scheme maintains high accuracy on smooth profile, preserves the positivity and can eliminate the oscillations in the vicinity of discontinuities while maintaining sharper discontinuity with superior solution quality compared to classical high accurate FV schemes.
Siengdy Tann, Xi Deng, Yuya Shimizu, Raphaël Loubère, Feng Xiao. Solution Property Preserving Reconstruction for Finite Volume Scheme: a BVD+MOOD framework. International Journal for Numerical Methods in Fluids, In press, ⟨10.1002/fld.4798⟩. ⟨hal-02397156⟩
Journal: International Journal for Numerical Methods in Fluids
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , 2019. ⟨hal-02265484⟩ Plus de détails...
An extended version of the hybrid recursive regularized Lattice-Boltzmann model which incorporates external force is developed to simulate humid air flows with phase change mechanisms under the Boussinesq approximation. Mass and momentum conservation equations are solved by a regu-larized lattice Boltzmann approach well suited for high Reynolds number flows, whereas the energy and humidity related equations are solved by a finite volume approach. Two options are investigated to account for cloud formation in atmospheric flow simulations. The first option considers a single conservation equation for total water and an appropriate invariant variable of temperature. In the other approach, liquid and vapor are considered via two separated equations, and phase transition is accounted for via a relaxation procedure. The obtained models are then systematically validated on four well-established benchmark problems including a double diffusive Rayleigh Bénard convection of humid air, 2D and 3D thermal moist rising bubble under convective atmospheric environment as well as a shallow cumulus convection in framework of large-eddy simulation.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , 2019. ⟨hal-02265484⟩
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , 2019. ⟨hal-02265484⟩ Plus de détails...
An extended version of the hybrid recursive regularized Lattice-Boltzmann model which incorporates external force is developed to simulate humid air flows with phase change mechanisms under the Boussinesq approximation. Mass and momentum conservation equations are solved by a regu-larized lattice Boltzmann approach well suited for high Reynolds number flows, whereas the energy and humidity related equations are solved by a finite volume approach. Two options are investigated to account for cloud formation in atmospheric flow simulations. The first option considers a single conservation equation for total water and an appropriate invariant variable of temperature. In the other approach, liquid and vapor are considered via two separated equations, and phase transition is accounted for via a relaxation procedure. The obtained models are then systematically validated on four well-established benchmark problems including a double diffusive Rayleigh Bénard convection of humid air, 2D and 3D thermal moist rising bubble under convective atmospheric environment as well as a shallow cumulus convection in framework of large-eddy simulation.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized lattice Boltzmann simulation of humid air with application to meteorological flows. Physical Review E , 2019. ⟨hal-02265484⟩
G. Farag, Pierre Boivin, P. Sagaut. Interaction of two-dimensional spots with a heat releasing/absorbing shock wave: linear interaction approximation results. Journal of Fluid Mechanics, 2019, 871, pp.865-895. ⟨10.1017/jfm.2019.324⟩. ⟨hal-02142649⟩ Plus de détails...
The canonical interaction between a two-dimensional weak Gaussian disturbance (en-tropy spot, density spot, weak vortex) with an exothermic/endothermic planar shock wave is studied via the Linear Interaction Approximation. To this end, a unified framework based on an extended Kovasznay decomposition that simultaneously accounts for non-acoustic density disturbances along with a poloidal-toroidal splitting of the vorticity mode and for heat-release is proposed. An extended version of Chu's definition for the energy of disturbances in compressible flows encompassing multi-component mixtures of gases is also proposed. This new definition precludes spurious non-normal phenomena when computing the total energy of extended Kovasznay modes. Detailed results are provided for three cases, along with fully general expressions for mixed solutions that combine incoming vortical, entropy and density disturbances.
G. Farag, Pierre Boivin, P. Sagaut. Interaction of two-dimensional spots with a heat releasing/absorbing shock wave: linear interaction approximation results. Journal of Fluid Mechanics, 2019, 871, pp.865-895. ⟨10.1017/jfm.2019.324⟩. ⟨hal-02142649⟩
Xi Deng, Pierre Boivin, Feng Xiao. A new formulation for two-wave Riemann solver accurate at contact interfaces. Physics of Fluids, 2019, 31 (4), pp.046102. ⟨10.1063/1.5083888⟩. ⟨hal-02100764⟩ Plus de détails...
This study proposes a new formulation for Harten, Lax and van Leer (HLL) type Riemann solver which is capable of solving contact discontinuities accurately but with robustness for strong shock. It is well known that the original HLL, which has incomplete wave structures, is too dissipative to capture contact disconti-nuities accurately. On the other side, contact-capturing approximate Riemann solvers such as Harten, Lax and van Leer with Contact (HLLC) usually suffer from spurious solutions, also called carbuncle phenomenon, for strong shock. In this work a new accurate and robust HLL-type formulation, so-called HLL-BVD (HLL Riemann solver with BVD) is proposed by modifying the original HLL with BVD (boundary variation dimin-shing) algorithm. Instead of explicitly recovering the complete wave structures like the way of HLLC, the proposed method restores the missing contact with a jump-like function. The capability of solving contact discontinuities is further improved by minimizing the inherent dissipation term in HLL. Without modifying the original incomplete wave structures of HLL, the robustness for strong shock has been reserved. Thus the proposed method is free from shock instability problem. The accuracy and robustness of the new method are demonstrated through solving several one-and two-dimensional tests. Results indicate that the new formulation based on two-wave HLL-type Riemann solver is not only capable of capturing contact waves more accurately than the original HLL or HLLC but, most importantly, is free form carbuncle instability for strong shock.
Xi Deng, Pierre Boivin, Feng Xiao. A new formulation for two-wave Riemann solver accurate at contact interfaces. Physics of Fluids, 2019, 31 (4), pp.046102. ⟨10.1063/1.5083888⟩. ⟨hal-02100764⟩
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩ Plus de détails...
In cross-flow membrane filtration, fouling results from material deposit which clogs the membrane inner surface. This hinders filtration, which experiences the so-called limiting flux. Among the models proposed by the literature, we retain a simple one: a steady-state reversible fouling is modelled with the use of a single additional parameter, i.e., N d , the ratio of the critical concentration for deposition to the feed concentration at inlet. To focus on fouling, viscous pressure drop and osmotic (counter-)pressure have been chosen low. It results in a minimal model of fouling. Solved thoroughly with the numerical means appropriate to enforce the nonlinear coupling between permeation and concentration polarization, the model delivers novel information. It first shows that permeation is utterly governed by solute transfer, the relevant non-dimensional quantities being hence limited to N d and Pe in , the transverse Péclet number. Furthermore, when the role played by N d and moderate Pe in (say Pe in < 40) is investigated, all results can be interpreted with the use of a single non-dimensional parameter, F l , the so-called fouling number, which simply reads F l ≡ Pe in N −1 d. Now rendered possible, the overall fit of the numerical data allows us to put forward analytical final expressions, which involve all the physical parameters and allow us to retrieve the experimental trends.
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩
Pierre Boivin, M.A. Cannac, O. Le Metayer. A thermodynamic closure for the simulation of multiphase reactive flows. International Journal of Thermal Sciences, 2019, 137, pp.640-649. ⟨hal-01981954⟩ Plus de détails...
A simple thermodynamic closure for the simulation of multiphase reactive flows is presented. It combines a fully explicit thermodynamic closure appropriate for weakly thermal multiphase flow simulations, with the classical variable heat capacity ideal gas thermodynamic closure, commonly used for reactive flows simulations. Each liquid and gas component is assumed to follow the recent Noble-Abel Stiffened Gas equation of state, fully described by a set of five parameters. A new method for setting these parameters is presented and validated through comparisons with NIST references. Comparisons with a well-known cubic equation of state, Soave-Redlich-Kwong, are also included. The Noble-Abel Stiffened-Gas equation of state is then extended as to cope with variable heat capacity, to make the mixture ther-modynamic closure appropriate for multiphase reactive flows.
Pierre Boivin, M.A. Cannac, O. Le Metayer. A thermodynamic closure for the simulation of multiphase reactive flows. International Journal of Thermal Sciences, 2019, 137, pp.640-649. ⟨hal-01981954⟩
Journal: International Journal of Thermal Sciences
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Plane-strain waves in nonlinear elastic solids with softening. Wave Motion, 2019, 89, pp.65-78. ⟨hal-02057946⟩ Plus de détails...
Propagation of elastic waves in damaged media (concrete, rocks) is studied theoretically and numerically. Such materials exhibit a nonlinear behavior, with long-time softening and recovery processes (slow dynamics). A constitutive model combining Murnaghan hyperelasticity with the slow dynamics is considered, where the softening is represented by the evolution of a scalar variable. The equations of motion in the Lagrangian framework are detailed. These equations are rewritten as a nonlinear hyperbolic system of balance laws, which is solved numerically using a finite-volume method with flux limiters. Numerical examples illustrate specific features of nonlinear elastic waves, as well as the effect of the material's softening. In particular, the generation of solitary waves in a periodic layered medium is illustrated numerically.
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Plane-strain waves in nonlinear elastic solids with softening. Wave Motion, 2019, 89, pp.65-78. ⟨hal-02057946⟩
L. Terrei, A. Lamorlette, Anne Ganteaume. Modelling the fire propagation from the fuel bed to the lower canopy of ornamental species used in wildland–urban interfaces. International Journal of Wildland Fire, 2019, 28 (2), pp.113. ⟨10.1071/WF18090⟩. ⟨hal-02176483⟩ Plus de détails...
South-eastern France is strongly affected by wildfires mostly occurring in the wildland-urban interfaces (WUIs). A WUI fire is often initiated in dead surface fuel, then can propagate to shrubs and trees when the lower canopy is close to (or touches) the ground. Whereas a previous study assessed the fire propagation from the fuel bed to the lower canopy of different species used as ornamental vegetation in this region, the objectives of the current work consisted of checking if the modelling of this fire propagation was possible using WFDS (Wildland-Urban Interface Fire Dynamical Simulator) in comparing experimental and modelling results. Experimental and modelling constraints (i. e. branch geometric definition, branch motion due to convection) showed differences in some of the recorded data (such as time to ignition, ignition temperature, mass loss and maximum temperature), but comparisons of variation in mass loss and temperature over time showed that modelling the fire propagation at the scale of a branch was possible if the branch fuel-moisture content remained lower than 25%. For both experiments and modelling, the ranking of species according to their branch flammability highlighted identical groups of species.
L. Terrei, A. Lamorlette, Anne Ganteaume. Modelling the fire propagation from the fuel bed to the lower canopy of ornamental species used in wildland–urban interfaces. International Journal of Wildland Fire, 2019, 28 (2), pp.113. ⟨10.1071/WF18090⟩. ⟨hal-02176483⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Premixed flame dynamics in presence of mist. Combustion Science and Technology, 2019, 191 (2), pp.197-207. ⟨10.1080/00102202.2018.1453728⟩. ⟨hal-01820207⟩ Plus de détails...
The injection of a water spray within an enclosure prone to explo- sion is reputed to reduce the risk. This strategy for safety improvement is at the root of numerous experiments that have concluded that pre- mixed flame can be extinguished by a sufficient amount of a water aerosol characterized by suitable droplet sizes. On the other hand, certain experiments seemingly indicate that flame speed promotion can be observed when particular water mists are injected within the premixture. To contribute to shed light upon these less than intuitive observa- tions, we propose to study the propagation of a nearly stoichiometric premixed flame within a 2D-lattice of water droplets. Main parameters of investigation are droplet size and droplet inter-distance (or equiva- lently, lattice spacing). When the droplet inter-distance is small, the results confirm that a sufficient amount of water quenches combustion. For larger droplet inter-distance, we observe a flame speed enhance- ment for suitable droplet size. Concomitantly, the flame front folds subjected to Darrieus-Landau instability. The final discussion, which invokes a Sivashinsky-type model equation for DL instability, interprets such a speed promotion in presence of mist as a secondary non-linear enhancement of the flame surface.
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Premixed flame dynamics in presence of mist. Combustion Science and Technology, 2019, 191 (2), pp.197-207. ⟨10.1080/00102202.2018.1453728⟩. ⟨hal-01820207⟩
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, 2019, 394, pp.82-99. ⟨hal-02142837⟩ Plus de détails...
A thermal lattice Boltzmann model with a hybrid recursive regularization (HRR) collision operator is developed on standard lattices for simulation of subsonic and sonic compressible flows without shock. The approach is hybrid: mass and momentum conservation equations are solved using a lattice Boltzmann solver, while the energy conservation is solved under entropy form with a finite volume solver. The defect of Galilean invariance related to Mach number is corrected by the third order equilibrium distribution function , supplemented by an additional correcting term and hybrid recursive regularization. The proposed approach is assessed considering the simulation of i) an isentropic vortex convection, ii) a two dimensional acoustic pulse and iii) non-isothermal Gaussian pulse with Ma number in range of 0 to 1. Numerical simulations demonstrate that the flaw in Galilean invari-ance is effectively eliminated by the compressible HRR model. At last, the compressible laminar flows over flat plate at Ma number of 0.3 and 0.87, Reynolds number of 10 5 are considered to validate the capture of viscous and diffusive effects.
Yongliang Feng, Pierre Boivin, Jérome Jacob, Pierre Sagaut. Hybrid recursive regularized thermal lattice Boltzmann model for high subsonic compressible flows. Journal of Computational Physics, 2019, 394, pp.82-99. ⟨hal-02142837⟩
Nicolas Frangieh, Dominique Morvan, Sofiane Meradji, Gilbert Accary, Oleg Bessonov. Numerical simulation of grassland fires behavior using an implicit physical multiphase model. Fire Safety Journal, 2018, 102, pp.37-47. ⟨10.1016/j.firesaf.2018.06.004⟩. ⟨hal-02114073⟩ Plus de détails...
12 This study reports 3D numerical simulations of the ignition and the propagation of 13 grassland fires. The mathematical model is based on a multiphase formulation and on a 14 homogenization approach that consists in averaging the conservation equations (mass, 15 momentum, energy …) governing the evolution of variables representing the state of the 16 vegetation/atmosphere system, inside a control volume containing both the solid-17 vegetation phase and the surrounding gaseous phase. This preliminary operation results 18 in the introduction of source/sink additional terms representing the interaction between 19 the gaseous phase and the solid-fuel particles. This study was conducted at large scale in 20 grassland because it represents the scale at which the behavior of the fire front presents 21 most similarities with full scale wildfires and also because of the existence of a large 22 number of relatively well controlled experiments performed in Australia and in the 23 United States. The simulations were performed for a tall grass, on a flat terrain, and for 24 six values of the 10-m open wind speed ranged between 1 and 12 m/s. The results are in 25 fairly good agreement with experimental data, with the predictions of operational 26 empirical and semi-empirical models, such as the McArthur model (MK5) in Australia and 27 the Rothermel model (BEHAVE) in USA, as well as with the predictions of other fully 3D 28 physical fire models (FIRETEC and WFDS). The comparison with the literature was 29 mainly based on the estimation of the rate of fire spread (ROS) and of the fire intensity, 30 as well as on the analysis of the fire-front shape. 31 32
Nicolas Frangieh, Dominique Morvan, Sofiane Meradji, Gilbert Accary, Oleg Bessonov. Numerical simulation of grassland fires behavior using an implicit physical multiphase model. Fire Safety Journal, 2018, 102, pp.37-47. ⟨10.1016/j.firesaf.2018.06.004⟩. ⟨hal-02114073⟩
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. LES in a Concentric Annular Pipe: Analysis of Mesh Sensitivity and Wall Pressure Fluctuations. Direct and Large-Eddy Simulation X, pp.93-100, 2018, 978-3-319-63211-7. ⟨hal-02111988⟩ Plus de détails...
Annular pipe flows have varied application in the domains of nuclear reactors, heat exchangers, drilling operations in oil industry etc.
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. LES in a Concentric Annular Pipe: Analysis of Mesh Sensitivity and Wall Pressure Fluctuations. Direct and Large-Eddy Simulation X, pp.93-100, 2018, 978-3-319-63211-7. ⟨hal-02111988⟩
Yongliang Feng, Muhammad Tayyab, Pierre Boivin. A Lattice-Boltzmann model for low-Mach reactive flows. Combustion and Flame, 2018, 196, pp.249 - 254. ⟨10.1016/j.combustflame.2018.06.027⟩. ⟨hal-01832640⟩ Plus de détails...
A new Lattice-Boltzmann model for low-Mach reactive flows is presented. Based on standard lattices, the model is easy to implement, and is the first, to the authors' knowledge, to pass the classical freely propagating flame test case as well as the counterflow diffusion flame, with strains up to extinction. For this presentation, simplified transport properties are considered, each species being assigned a separate Lewis number. In addition, the gas mixture is assumed to be calorically perfect. Comparisons with reference solutions show excellent agreement for mass fraction profiles, flame speed in premixed mixtures, as well as maximum temperature dependence with strain rate in counterflow diffusion flames.
Yongliang Feng, Muhammad Tayyab, Pierre Boivin. A Lattice-Boltzmann model for low-Mach reactive flows. Combustion and Flame, 2018, 196, pp.249 - 254. ⟨10.1016/j.combustflame.2018.06.027⟩. ⟨hal-01832640⟩
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh, Oleg Bessonov. A 3D physical model to study the behavior of vegetation fires at laboratory scale. Fire Safety Journal, 2018, 101, pp.39-52. ⟨10.1016/j.firesaf.2018.08.011⟩. ⟨hal-02114685⟩ Plus de détails...
A 3D multi-physical model referred to as “FireStar3D” has been developed in order to predict the behavior of wildfires at a local scale (<500 m). In the continuity of a previous work limited to 2D configurations, this model consists of solving the conservation equations of the coupled system composed of the vegetation and the surrounding gaseous medium. In particular, the model is able to account explicitly for all the mechanisms of degradation of the vegetation (by drying, pyrolysis, and heterogeneous combustion) and the various interactions between the gas mixture (ambient air + pyrolysis and combustion products) and the vegetation cover such as drag force, heat transfer by convection and radiation, and mass transfer. Compared to previous works, some new features were introduced in the modeling of the surface combustion of charcoal, the calculation of the heat transfer coefficient between the solid fuel particles and the surrounding atmosphere, and many improvements were brought to the numerical method to enable affordable 3D simulations. The partial validation of the model was based on some comparisons with experimental data collected at small scale fires carried out in the Missoula Fire Sciences Lab's wind tunnel, through various solid-fuel layers and in well controlled conditions. A relative good agreement was obtained for most of the simulations that were conducted. A parametric study of the dependence of the rate of spread on the wind speed and on the fuelbed characteristics is presented.
Dominique Morvan, Gilbert Accary, Sofiane Meradji, Nicolas Frangieh, Oleg Bessonov. A 3D physical model to study the behavior of vegetation fires at laboratory scale. Fire Safety Journal, 2018, 101, pp.39-52. ⟨10.1016/j.firesaf.2018.08.011⟩. ⟨hal-02114685⟩
Pierre Boivin, Forman A. Williams. Extension of a wide-range three-step hydrogen mechanism to syngas. Combustion and Flame, 2018, 196, pp.85-87. ⟨10.1016/j.combustflame.2018.05.034⟩. ⟨hal-02112081⟩ Plus de détails...
Previously we have shown how a single species X can be introduced, representing either HO 2 for high-temperature ignition or H 2 O 2 for low-temperature ignition, to develop an algorithm that covers the entire range of ignition, flame-propagation, and combustion conditions, without a significant degradation of accuracy, for hydrogen-air systems. By adding relevant CO chemistry to the hydrogen chemistry, this same approach can be applied to derive a comparably useful four-step reduced-chemistry description for syngas blends that have small enough concentrations of methane, other hydrocarbons , or other reactive species to be dominated by the elementary steps of the H 2 /CO system. The present communication reports the resulting extended algorithm. This work begins with the elementary steps of the detailed chemistry as listed in Table 1. We shall employ the numbering of the steps as given in the table, which identifies the 8 steps that are considered to be reversible and gives fitted parameters for the reverses of those steps.
Pierre Boivin, Forman A. Williams. Extension of a wide-range three-step hydrogen mechanism to syngas. Combustion and Flame, 2018, 196, pp.85-87. ⟨10.1016/j.combustflame.2018.05.034⟩. ⟨hal-02112081⟩
Stéphane Abide, Stéphane Viazzo, Isabelle Raspo, Anthony Randriamampianina. Higher-order compact scheme for high-performance computing of stratified rotating flows. Computers and Fluids, 2018, 174, pp.300-310. ⟨10.1016/j.compfluid.2018.07.016⟩. ⟨hal-02111489⟩ Plus de détails...
To take advantage of modern generation computing hardware, a scalable numerical method, based on higher-order compact scheme, is described to solve rotating stratified flows in cylindrical annular domains. An original approach combining 2d-pencil decomposition and reduced Parallel Diagonal Dominant is proposed to improve the parallelization performance during the computation of Poisson/Helmholtz solvers and time explicit terms. The developed technique is validated with respect to analytical solutions, using the method of manufactured solutions, and available data for two specific configurations. The purpose is to demonstrate its ability to correctly capture the flow characteristics in strato-rotational instability and in baroclinic instability with associated small-scale features. Moreover, this code is found to drastically reduce the huge execution times often preventing detailed numerical investigations of these complex phenomena. Strong scaling test is carried out to assess the performance for up to 1024 cores using grid up to 128 × 568 × 568 in radial, axial and azimuthal directions.
Stéphane Abide, Stéphane Viazzo, Isabelle Raspo, Anthony Randriamampianina. Higher-order compact scheme for high-performance computing of stratified rotating flows. Computers and Fluids, 2018, 174, pp.300-310. ⟨10.1016/j.compfluid.2018.07.016⟩. ⟨hal-02111489⟩
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Reprint of: Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, 2018, 169, pp.213-229. ⟨10.1016/j.compfluid.2018.03.054⟩. ⟨hal-02115861⟩ Plus de détails...
Hot spots ignition and shock to detonation transition modeling in pressed explosives is addressed in the frame of multiphase flow theory. Shock propagation results in mechanical disequilibrium effects between the condensed phase and the gas trapped in pores. Resulting subscale motion creates hot spots at pore scales. Pore collapse is modeled as a pressure relaxation process, during which dissipated power by the ‘configuration’ pressure produces local heating. Such an approach reduces 3D micromechanics and subscale contacts effects to a ‘granular’ equation of state. Hot spots criticity then results of the competition between heat deposition and conductive losses. Heat losses between the hot solid-gas interface at pore's scale and the colder solid core grains are determined through a subgrid model using two energy equations for the solid phase. The conventional energy balance equation provides the volume average solid temperature and a non-conventional energy equation provides the solid core temperature that accounts for shock heating. With the help of these two temperatures and subscale reconstruction, the interface temperature is determined as well as interfacial heat loss. The overall flow model thus combines a full disequilibrium two-phase model for the mean solid-gas flow variables with a subgrid model, aimed to compute local solid-gas interface temperature. Its evolution results of both subscale motion dissipation and conductive heat loss. The interface temperature serves as ignition criterion for the solid material deflagration. There is no subscale mesh, no system of partial differential equations solved at grain scale. The resulting model contains less parameter than existing ones and associates physical meaning to each of them. It is validated against experiments in two very different regimes: Shock to detonation transition, that typically happens in pressure ranges of 50 kbar and shock propagation that involves pressure ranges 10 times higher.
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Reprint of: Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, 2018, 169, pp.213-229. ⟨10.1016/j.compfluid.2018.03.054⟩. ⟨hal-02115861⟩
H Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A Finite-Volume Approach to 1D Nonlinear Elastic Waves: Application to Slow Dynamics. Acta Acustica united with Acustica, 2018, ⟨10.3813/Aaa.919197⟩. ⟨hal-02111888⟩ Plus de détails...
A numerical method for longitudinal wave propagation in nonlinear elastic solids is presented. Here, we consider polynomial stress-strain relationships, which are widely used in nondestructive evaluation. The large-strain and infinitesimal-strain constitutive laws deduced from Murnaghan'sl aw are detailed, and polynomial expressions are obtained. The Lagrangian equations of motion yield ahyperbolic system of conservation laws. The latter is solved numerically using afi nite-volume method with flux limiters based on Roe linearization. The method is tested on the Riemann problem, which yields nonsmooth solutions. The method is then applied to acontinuum model with one scalar internal variable, accounting for the softening of the material (slowdynamics).
H Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A Finite-Volume Approach to 1D Nonlinear Elastic Waves: Application to Slow Dynamics. Acta Acustica united with Acustica, 2018, ⟨10.3813/Aaa.919197⟩. ⟨hal-02111888⟩
Mohamad El Houssami, Aymeric Lamorlette, Dominique Morvan, Rory M Hadden, Albert Simeoni. Framework for submodel improvement in wildfire modeling. Combustion and Flame, 2018, 190, pp.12-24. ⟨10.1016/j.combustflame.2017.09.038⟩. ⟨hal-02114000⟩ Plus de détails...
An experimental and numerical study was carried out to assess the performance of the different sub-models and parameters used to describe the burning dynamics of wildfires. A multiphase formulation was used and compared to static fires of dried pitch pine needles of different bulk densities. The samples were exposed to an external heat flux of 50 kW/m 2 in the FM Global Fire Propagation Apparatus and subjected to different airflows, providing a controlled environment and repeatable conditions. Sub-models for convective heat transfer, drag forces, and char combustion were investigated to provide mass loss rate, flaming duration, and gas emissions. Good agreement of predicted mass loss rates and heat release rates was achieved, where all these submodels were selected to suit the tested conditions. Simulated flaming times for different flow conditions and different fuel bulk densities compared favorably against experimental measurements. The calculation of the drag forces and the heat transfer coefficient was demonstrated to influence greatly the heating/cooling rate, the degradation rate, and the flaming time. The simulated CO and CO 2 values compared well with experimental data, especially for reproducing the transition between flaming and smoldering. This study complements a previous study made with no flow to propose a systematic approach that can be used to assess the performance of the submodels and to better understand how specific physical phenomena contribute to the wildfire dynamics. Furthermore, this study underlined the importance of selecting relevant submodels and the necessity of introducing relevant subgrid-scale modelling for larger scale simulations.
Mohamad El Houssami, Aymeric Lamorlette, Dominique Morvan, Rory M Hadden, Albert Simeoni. Framework for submodel improvement in wildfire modeling. Combustion and Flame, 2018, 190, pp.12-24. ⟨10.1016/j.combustflame.2017.09.038⟩. ⟨hal-02114000⟩
Evelyne Neau, Christophe Nicolas, Laurent Avaullée. Extension of the group contribution NRTL-PRA EoS for the modeling of mixtures containing light gases and alcohols with water and salts. Fluid Phase Equilibria, 2018, 458, pp.194-210. ⟨10.1016/j.fluid.2017.09.028⟩. ⟨hal-01703014⟩ Plus de détails...
The offshore exploitation of petroleum fluids in normal conditions of pressure and temperature of transport and in presence of salt water is concerned with the prevention of gas hydrate formation, generally thanks to continuous injection of inhibitors, or punctual injection of methanol in start-up and shut-down operations. Hence, models of interest should provide both, satisfactory phase equilibrium estimations of hydrocarbon and alcohol mixtures with water and reliable predictions of their behavior in presence of salts.
Evelyne Neau, Christophe Nicolas, Laurent Avaullée. Extension of the group contribution NRTL-PRA EoS for the modeling of mixtures containing light gases and alcohols with water and salts. Fluid Phase Equilibria, 2018, 458, pp.194-210. ⟨10.1016/j.fluid.2017.09.028⟩. ⟨hal-01703014⟩
Richard Saurel, Carlos Pantano. Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows. Annual Review of Fluid Mechanics, 2018, 50 (1), pp.105 - 130. ⟨10.1146/annurev-fluid-122316-050109⟩. ⟨hal-02115896⟩ Plus de détails...
Simulation of compressible flows became a routine activity with the appearance of shock-/contact-capturing methods. These methods can determine all waves, particularly discontinuous ones. However, additional difficulties may appear in two-phase and multimaterial flows due to the abrupt variation of thermodynamic properties across the interfacial region, with discontinuous thermodynamical representations at the interfaces. To overcome this difficulty, researchers have developed augmented systems of governing equations to extend the capturing strategy. These extended systems, reviewed here, are termed diffuse-interface models, because they are designed to compute flow variables correctly in numerically diffused zones surrounding interfaces. In particular, they facilitate coupling the dynamics on both sides of the (diffuse) interfaces and tend to the proper pure fluid–governing equations far from the interfaces. This strategy has become efficient for contact interfaces separating fluids that are governed by different equations of state, in the presence or absence of capillary effects, and with phase change. More sophisticated materials than fluids (e.g., elastic–plastic materials) have been considered as well.
Richard Saurel, Carlos Pantano. Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows. Annual Review of Fluid Mechanics, 2018, 50 (1), pp.105 - 130. ⟨10.1146/annurev-fluid-122316-050109⟩. ⟨hal-02115896⟩
Dominique Morvan, Nicolas Frangieh. Wildland fires behaviour: wind effect versus Byram’s convective number and consequences upon the regime of propagation. International Journal of Wildland Fire, 2018, 27 (9), pp.636. ⟨10.1071/Wf18014⟩. ⟨hal-02114689⟩ Plus de détails...
With fuel moisture content and slope, wind velocity (U W) is one of the major physical parameters that most affects the behaviour of wildland fires. The aim of this short paper was to revisit the relationship between the rate of spread (ROS) and the wind velocity, through the role played by the two forces governing the trajectory of the flame front and the plume, i.e. the buoyancy of the plume and the inertia due to wind. A large set of experimental data (at field and laboratory scale) from the literature was analysed, by introducing the ratio between these two forces, namely Byram's convective number N C and considering the relationship between the fire ROS/wind speed ratio and Byram's number. This short note was also an opportunity to make a point on particular issues, such as the existence of two regimes of propagation of surface fires (wind-driven fire vs plume-dominated fire), the relative importance of the two modes of heat transfer (by convection and radiation) on the propagation of a fire front, and others scientific debates animating the wildland fire community.
Dominique Morvan, Nicolas Frangieh. Wildland fires behaviour: wind effect versus Byram’s convective number and consequences upon the regime of propagation. International Journal of Wildland Fire, 2018, 27 (9), pp.636. ⟨10.1071/Wf18014⟩. ⟨hal-02114689⟩
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with
reactive fronts. Computers and Fluids, Elsevier, In press, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-01791898⟩ Plus de détails...
This work proposes a new spatial reconstruction scheme in finite volume frameworks. Different from long-lasting reconstruction processes which employ high order polynomials enforced with some carefully designed limiting pro- jections to seek stable solutions around discontinuities, the current discretized scheme employs THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive sharpness to solve both smooth and discontinuous solutions. Due to the essentially monotone and bounded properties of THINC function, difficulties to solve sharp discontinuous solutions and complexities associated with designing limiting projections can be prevented. A new simplified BVD (Boundary Variations Diminishing) algorithm, so-called adaptive THINC-BVD, is devised to reduce numerical dissipations through minimizing the total boundary variations for each cell. Verified through numerical tests, the present method is able to capture both smooth and discontinuous solutions in Euler equations for com- pressible gas dynamics with excellent solution quality competitive to other existing schemes. More profoundly, it provides an accurate and reliable solver for a class of reactive compressible gas flows with stiff source terms, such as the gaseous detonation waves, which are quite challenging to other high-resolution schemes. The stiff C-J detonation benchmark test reveals that the adaptive THINC-BVD scheme can accurately capture the reacting front of the gaseous detonation, while the WENO scheme with the same grid resolution generates unacceptable results. Owing also to its algorithmic simplicity, the proposed method can become as a practical and promising numerical solver for compress- ible gas dynamics, particularly for simulations involving strong discontinuities and reacting fronts with stiff source term.
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with
reactive fronts. Computers and Fluids, Elsevier, In press, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-01791898⟩
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Modeling longitudinal wave propagation in nonlinear viscoelastic solids with softening. International Journal of Solids and Structures, 2018, 141-142, pp.35-44. ⟨10.1016/j.ijsolstr.2018.02.009⟩. ⟨hal-01701624⟩ Plus de détails...
A model for longitudinal wave propagation in rocks and concrete is presented. Such materials are known to soften under a dynamic loading, i.e. the speed of sound diminishes with forcing amplitudes. Also known as slow dynamics, the softening of the material is not instantaneous. Based on continuum mechanics with internal variables of state, a new formulation is proposed, which accounts for nonlinear Zener viscoelasticity and softening. A finite-volume method using Roe linearization is developed for the system of partial differential equations so-obtained. The method is used to carry out resonance simulations, and its performance is assessed in the linear viscoelastic case. Qualitative agreement with experimental results of nonlinear ultrasound spectroscopy (NRUS) and dynamic acousto-elastic testing (DAET) is obtained.
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. Modeling longitudinal wave propagation in nonlinear viscoelastic solids with softening. International Journal of Solids and Structures, 2018, 141-142, pp.35-44. ⟨10.1016/j.ijsolstr.2018.02.009⟩. ⟨hal-01701624⟩
Journal: International Journal of Solids and Structures
William Mell, Albert Simeoni, Dominique Morvan, J. Kevin Kevin Hiers, Nicholas Skowronski, et al.. Clarifying the meaning of mantras in wildland fire behaviour modelling: reply to Cruz et al. (2017). International Journal of Wildland Fire, 2018, 27 (11), pp.770. ⟨10.1071/Wf18106⟩. ⟨hal-02114662⟩ Plus de détails...
In a recent communication, Cruz et al. (2017) called attention to several recurring statements (mantras) in the wildland fire literature regarding empirical and physical fire behaviour models. Motivated by concern that these mantras have not been fully vetted and are repeated blindly, Cruz et al. (2017) sought to verify five mantras they identify. This is a worthy goal and here we seek to extend the discussion and provide clarification to several confusing aspects of the Cruz et al. (2017) communication. In particular, their treatment of what they call physical models is inconsistent, neglects to reference current research activity focussed on combined experimentation and model development, and misses an opportunity to discuss the potential use of physical models to fire behaviour outside the scope of empirical approaches.
William Mell, Albert Simeoni, Dominique Morvan, J. Kevin Kevin Hiers, Nicholas Skowronski, et al.. Clarifying the meaning of mantras in wildland fire behaviour modelling: reply to Cruz et al. (2017). International Journal of Wildland Fire, 2018, 27 (11), pp.770. ⟨10.1071/Wf18106⟩. ⟨hal-02114662⟩
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A finite-volume approach to 1D nonlinear elastic waves: Application to slow dynamics. Acta Acustica united with Acustica, 2018, 104, pp.561-570. ⟨hal-01806373⟩ Plus de détails...
A numerical method for longitudinal wave propagation in nonlinear elastic solids is presented. Here, we consider polynomial stress-strain relationships, which are widely used in nondestructive evaluation. The large-strain and infinitesimal-strain constitutive laws deduced from Murnaghan's law are detailed , and polynomial expressions are obtained. The Lagrangian equations of motion yield a hyperbolic system of conservation laws. The latter is solved numerically using a finite-volume method with flux limiters based on Roe linearization. The method is tested on the Riemann problem, which yields nonsmooth solutions. The method is then applied to a continuum model with one scalar internal variable, accounting for the softening of the material (slow dynamics).
Harold Berjamin, Bruno Lombard, Guillaume Chiavassa, Nicolas Favrie. A finite-volume approach to 1D nonlinear elastic waves: Application to slow dynamics. Acta Acustica united with Acustica, 2018, 104, pp.561-570. ⟨hal-01806373⟩
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with
reactive fronts. Computers and Fluids, Elsevier, In press, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-01791898⟩ Plus de détails...
This work proposes a new spatial reconstruction scheme in finite volume frameworks. Different from long-lasting reconstruction processes which employ high order polynomials enforced with some carefully designed limiting pro- jections to seek stable solutions around discontinuities, the current discretized scheme employs THINC (Tangent of Hyperbola for INterface Capturing) functions with adaptive sharpness to solve both smooth and discontinuous solutions. Due to the essentially monotone and bounded properties of THINC function, difficulties to solve sharp discontinuous solutions and complexities associated with designing limiting projections can be prevented. A new simplified BVD (Boundary Variations Diminishing) algorithm, so-called adaptive THINC-BVD, is devised to reduce numerical dissipations through minimizing the total boundary variations for each cell. Verified through numerical tests, the present method is able to capture both smooth and discontinuous solutions in Euler equations for com- pressible gas dynamics with excellent solution quality competitive to other existing schemes. More profoundly, it provides an accurate and reliable solver for a class of reactive compressible gas flows with stiff source terms, such as the gaseous detonation waves, which are quite challenging to other high-resolution schemes. The stiff C-J detonation benchmark test reveals that the adaptive THINC-BVD scheme can accurately capture the reacting front of the gaseous detonation, while the WENO scheme with the same grid resolution generates unacceptable results. Owing also to its algorithmic simplicity, the proposed method can become as a practical and promising numerical solver for compress- ible gas dynamics, particularly for simulations involving strong discontinuities and reacting fronts with stiff source term.
Xi Deng, Bin Xie, R. Loubère, Yuya Shimizu, Feng Xiao. Limiter-free discontinuity-capturing scheme for compressible gas dynamics with
reactive fronts. Computers and Fluids, Elsevier, In press, 171, pp.1-14. ⟨10.1016/j.compfluid.2018.05.015⟩. ⟨hal-01791898⟩
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small-scale waves within the Stewartson layers of a thermally driven rotating annulus. Journal of Fluid Mechanics, 2018, 841, pp.380 - 407. ⟨10.1017/jfm.2018.10⟩. ⟨hal-02116196⟩ Plus de détails...
We report on small-scale instabilities in a thermally driven rotating annulus filled with a liquid with moderate Prandtl number. The study is based on direct numerical simulations and an accompanying laboratory experiment. The computations are performed independently with two different flow solvers, that is, first, the non-oscillatory forward-in-time differencing flow solver EULAG and, second, a higher-order finite-difference compact scheme (HOC). Both branches consistently show the occurrence of small-scale patterns at both vertical sidewalls in the Stewartson layers of the annulus. Small-scale flow structures are known to exist at the inner sidewall. In contrast, short-period waves at the outer sidewall have not yet been reported. The physical mechanisms that possibly trigger these patterns are discussed. We also debate whether these small-scale structures are a gravity wave signal.
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small-scale waves within the Stewartson layers of a thermally driven rotating annulus. Journal of Fluid Mechanics, 2018, 841, pp.380 - 407. ⟨10.1017/jfm.2018.10⟩. ⟨hal-02116196⟩
Dominique Morvan. Comprendre et prévenir les feux de végétation. Université Grenoble Alpes. Encyclopédie de l’Environnement, , 2018. ⟨hal-01678486⟩ Plus de détails...
L’amélioration des politiques de prévention et de réduction du risque incendie en milieu naturel et dans les zones périurbaines nécessite une compréhension approfondie des facteurs qui vont contribuer à l’ignition d’un premier foyer puis à sa propagation sous la forme d’un front de flamme. La dynamique d’un incendie et son impact sur un environnement donné dépendent de différents paramètres, tels que la structure de la strate combustible (herbe, arbustes, arbres), les facteurs de stress auxquels est soumise la végétation (teneur en eau, humidité relative et température de l’air ambiant, vent, pente du terrain), la nature exacte de l’espace impacté (savane, maquis, forêt, zone péri-urbaine). On sait déjà que la puissance maximale atteinte par certains feux dépasse très largement les limites d’efficacité des moyens de lutte les plus puissants (hélicoptères, bombardiers à eau). C’est pour cette raison que les services de lutte, un peu partout dans le monde, ont mis en place depuis de nombreuses années une stratégie basée sur l’attaque précoce des feux naissants. L’efficacité de cette approche semble à présent atteindre ses limites, elle commence même à produire des effets négatifs. En effet, l’élimination systématique des feux de faible intensité a pour première conséquence de favoriser l’accumulation de biomasse au sol et par ce biais d’aggraver un facteur de risque important.
Dominique Morvan. Comprendre et prévenir les feux de végétation. Université Grenoble Alpes. Encyclopédie de l’Environnement, , 2018. ⟨hal-01678486⟩
Aymeric Lamorlette, Mohamad El Houssami, Dominique Morvan. An improved non-equilibrium model for the ignition of living fuel. International Journal of Wildland Fire, 2018, 27 (1), pp.29-41. ⟨10.1071/Wf17020⟩. ⟨hal-02114417⟩ Plus de détails...
This paper deals with the modelling of living fuel ignition, suggesting that an accurate description using a multiphase formulation requires consideration of a thermal disequilibrium within the vegetation particle, between the solid (wood) and the liquid (sap). A simple model at particle scale is studied to evaluate the flux distribution between phases in order to split the net flux on the particles into the two sub-phases. An analytical solution for the split function is obtained from this model and is implemented in ForestFireFOAM, a computational fluid dynamics (CFD) solver dedicated to vegetation fire simulations, based on FireFOAM. Using this multiphase formulation, simulations are run and compared with existing data on living fuel flammability. The following aspects were considered: fuel surface temperature, ignition, flaming combustion time, mean and peak heat release rate (HRR). Acceptable results were obtained, suggesting that the thermal equilibrium might not be an acceptable assumption to properly model ignition of living fuel.
Aymeric Lamorlette, Mohamad El Houssami, Dominique Morvan. An improved non-equilibrium model for the ignition of living fuel. International Journal of Wildland Fire, 2018, 27 (1), pp.29-41. ⟨10.1071/Wf17020⟩. ⟨hal-02114417⟩
Dominique Morvan. Comprendre et prévenir les feux de végétation. Université Grenoble Alpes. Encyclopédie de l’Environnement, , 2018. ⟨hal-01678486⟩ Plus de détails...
L’amélioration des politiques de prévention et de réduction du risque incendie en milieu naturel et dans les zones périurbaines nécessite une compréhension approfondie des facteurs qui vont contribuer à l’ignition d’un premier foyer puis à sa propagation sous la forme d’un front de flamme. La dynamique d’un incendie et son impact sur un environnement donné dépendent de différents paramètres, tels que la structure de la strate combustible (herbe, arbustes, arbres), les facteurs de stress auxquels est soumise la végétation (teneur en eau, humidité relative et température de l’air ambiant, vent, pente du terrain), la nature exacte de l’espace impacté (savane, maquis, forêt, zone péri-urbaine). On sait déjà que la puissance maximale atteinte par certains feux dépasse très largement les limites d’efficacité des moyens de lutte les plus puissants (hélicoptères, bombardiers à eau). C’est pour cette raison que les services de lutte, un peu partout dans le monde, ont mis en place depuis de nombreuses années une stratégie basée sur l’attaque précoce des feux naissants. L’efficacité de cette approche semble à présent atteindre ses limites, elle commence même à produire des effets négatifs. En effet, l’élimination systématique des feux de faible intensité a pour première conséquence de favoriser l’accumulation de biomasse au sol et par ce biais d’aggraver un facteur de risque important.
Dominique Morvan. Comprendre et prévenir les feux de végétation. Université Grenoble Alpes. Encyclopédie de l’Environnement, , 2018. ⟨hal-01678486⟩
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩ Plus de détails...
Membrane solute permeability plays a role in the buildup of concentration polarization in pressure-driven crossflow filtration processes, and thus in the determination of the permeate flux, solute rejection, retentate flux and concentration. We numerically examine reverse-osmosis desalination with membranes of fixed solvent permeability, but of variable selectivity with respect to the solute. The study highlights an intricate coupling between retentate and filtrate properties. In particular, it reveals that, for given values of solute permeability and feed concentration, there is a maximum operating pressure that optimizes solute rejection regardless of the feed salinity. The conditions leading to this and to other peculiar behaviors for permeation fluxes and concentrations are identified.
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, 2017, 159, pp.95 - 111. ⟨10.1016/j.compfluid.2017.09.006⟩. ⟨hal-01707909⟩ Plus de détails...
Hot spots ignition and shock to detonation transition modeling in pressed explosives is addressed in the frame of multiphase flow theory. Shock propagation results in mechanical disequilibrium effects between the condensed phase and the gas trapped in pores. Resulting subscale motion creates hot spots at pore scales. Pore collapse is modeled as a pressure relaxation process, during which dissipated power by the ‘configuration’ pressure produces local heating. Such an approach reduces 3D micromechanics and subscale contacts effects to a ‘granular’ equation of state. Hot spots criticity then results of the competition between heat deposition and conductive losses. Heat losses between the hot solid-gas interface at pore's scale and the colder solid core grains are determined through a subgrid model using two energy equations for the solid phase. The conventional energy balance equation provides the volume average solid temperature and a non-conventional energy equation provides the solid core temperature that accounts for shock heating. With the help of these two temperatures and subscale reconstruction, the interface temperature is determined as well as interfacial heat loss. The overall flow model thus combines a full disequilibrium two-phase model for the mean solid-gas flow variables with a subgrid model, aimed to compute local solid-gas interface temperature. Its evolution results of both subscale motion dissipation and conductive heat loss. The interface temperature serves as ignition criterion for the solid material deflagration. There is no subscale mesh, no system of partial differential equations solved at grain scale. The resulting model contains less parameter than existing ones and associates physical meaning to each of them. It is validated against experiments in two very different regimes: Shock to detonation transition, that typically happens in pressure ranges of 50 kbar and shock propagation that involves pressure ranges 10 times higher.
Richard Saurel, François Fraysse, Damien Furfaro, Emmanuel Lapebie. Multiscale multiphase modeling of detonations in condensed energetic materials. Computers and Fluids, 2017, 159, pp.95 - 111. ⟨10.1016/j.compfluid.2017.09.006⟩. ⟨hal-01707909⟩
Alexandre Chiapolino, Richard Saurel, Boniface Nkonga. Sharpening diffuse interfaces with compressible fluids on unstructured meshes. Journal of Computational Physics, 2017, 340, pp.389-417. ⟨hal-01589124⟩ Plus de détails...
Richard Saurel, Ashwin Chinnayya, Quentin Carmouze. Modelling compressible dense and dilute two-phase flows. Physics of Fluids, 2017, 29 (6), pp.063301. ⟨10.1063/1.4985289⟩. ⟨hal-01678274⟩ Plus de détails...
Many two-phase flow situations, from engineering science to astrophysics, deal with transition from dense (high concentration of the condensed phase) to dilute concentration (low concentration of the same phase), covering the entire range of volume fractions. Some models are now well accepted at the two limits, but none are able to cover accurately the entire range, in particular regarding waves propagation. In the present work, an alternative to the Baer and Nunziato (BN) model [Baer, M. R. and Nunziato, J. W., “A two-phase mixture theory for the deflagration-to-detonation transition (DDT) in reactive granular materials,” Int. J. Multiphase Flow 12(6), 861 (1986)], initially designed for dense flows, is built. The corresponding model is hyperbolic and thermodynamically consistent. Contrarily to the BN model that involves 6 wave speeds, the new formulation involves 4 waves only, in agreement with the Marble model [Marble, F. E., “Dynamics of a gas containing small solid particles,” Combustion and Propulsion (5th AGARD Colloquium) (Pergamon Press, 1963), Vol. 175] based on pressureless Euler equations for the dispersed phase, a well-accepted model for low particle volume concentrations. In the new model, the presence of pressure in the momentum equation of the particles and consideration of volume fractions in the two phases render the model valid for large particle concentrations. A symmetric version of the new model is derived as well for liquids containing gas bubbles. This model version involves 4 characteristic wave speeds as well, but with different velocities. Last, the two sub-models with 4 waves are combined in a unique formulation, valid for the full range of volume fractions. It involves the same 6 wave speeds as the BN model, but at a given point of space, 4 waves only emerge, depending on the local volume fractions. The non-linear pressure waves propagate only in the phase with dominant volume fraction. The new model is tested numerically on various test problems ranging from separated phases in a shock tube to shock–particle cloud interaction. Its predictions are compared to BN and Marble models as well as against experimental data showing clear improvements.
Richard Saurel, Ashwin Chinnayya, Quentin Carmouze. Modelling compressible dense and dilute two-phase flows. Physics of Fluids, 2017, 29 (6), pp.063301. ⟨10.1063/1.4985289⟩. ⟨hal-01678274⟩
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, 2017, 90, pp.54 - 61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩ Plus de détails...
Several studies in the literature explore the connection between rate of spread (ROS) and wind in wildland fires. These studies show very different positions about the role of radiation and convection as heat transfer mechanisms. In the case when the fuel bed is well-ordered and vertically-oriented, there seems to be a consensus leading to suggest that convective heating is the dominant heat transfer mode in that case. The purpose of this work is to propose a convective semi-physical model for the behaviour of the rate of spread in wind, when the fuel bed is vertically-oriented. Due to a specific fuel bed arrangement, flame radiation -i.e. radiation from the part of the flame above the vegetal stratum is neglected. Only horizontal radiation from the fuel burning particles area and convective heating are taken into account. Convective heat transfer is assumed to be the primary heat transfer mechanism. The proposed model is confronted to 172 laboratory fires with a wide range of fuel characteristics. The predicted results are also compared with two simplified models from the literature. Statistical tools are used to check the agreement between the predicted ROS and the observed one where a strong agreement is generally observed, irrespective of fuel bed characteristics.
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, 2017, 90, pp.54 - 61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, 2017, 90, pp.54-61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩ Plus de détails...
Several studies in the literature explore the connection between rate of spread (ROS) and wind in wildland fires. These studies show very different positions about the role of radiation and convection as heat transfer mechanisms. In the case when the fuel bed is well-ordered and vertically-oriented, there seems to be a consensus leading to suggest that convective heating is the dominant heat transfer mode in that case. The purpose of this work is to propose a convective semi-physical model for the behaviour of the rate of spread in wind, when the fuel bed is vertically-oriented. Due to a specific fuel bed arrangement, flame radiation -i.e. radiation from the part of the flame above the vegetal stratum is neglected. Only horizontal radiation from the fuel burning particles area and convective heating are taken into account. Convective heat transfer is assumed to be the primary heat transfer mechanism. The proposed model is confronted to 172 laboratory fires with a wide range of fuel characteristics. The predicted results are also compared with two simplified models from the literature. Statistical tools are used to check the agreement between the predicted ROS and the observed one where a strong agreement is generally observed, irrespective of fuel bed characteristics.
François Joseph Chatelon, Jacques Henri Balbi, Dominique Morvan, Jean Louis Rossi, Thierry Marcelli. A convective model for laboratory fires with well-ordered vertically-oriented fuel beds. Fire Safety Journal, 2017, 90, pp.54-61. ⟨10.1016/j.firesaf.2017.04.022⟩. ⟨hal-01590266⟩
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. Comparative study of the contribution of various PWR spacer grid components to hydrodynamic and wall pressure characteristics. Nuclear Engineering and Design, 2017, 317, pp.22-43. ⟨10.1016/j.nucengdes.2017.03.011⟩. ⟨hal-01590274⟩ Plus de détails...
Flow-induced vibrations in a pressurized water reactor (PWR) core can cause fretting wear in fuel rods. These vibrations can compromise safety of a nuclear reactor. So, it is necessary to know the random fluctuating forces acting on the rods which cause these vibrations. In this paper, simplified 3D models like square spacer grid, circular spacer grid and symmetric mixing vanes have been used inside an annular pipe. Hydrodynamic and wall pressure characteristics are evaluated using large eddy simulations (LES). Structured meshes are generated as far as possible. Simulations are compared with an experiment. Results show that the grid and vanes have a combined effect: grid accelerates the flow whereas the vanes contribute to the swirl structures. Spectral analysis of the simulations illustrate vortex shedding phenomenon in the wake of spacer grids. This initial study opens up interesting perspectives towards improving the modeling strategy and understanding the complex phenomenon inside a PWR core.
Saptarshi Bhattacharjee, Guillaume Ricciardi, Stéphane Viazzo. Comparative study of the contribution of various PWR spacer grid components to hydrodynamic and wall pressure characteristics. Nuclear Engineering and Design, 2017, 317, pp.22-43. ⟨10.1016/j.nucengdes.2017.03.011⟩. ⟨hal-01590274⟩
Jonathan Gubspun, Marc Georgelin, Julien Deschamps, Marc Leonetti, Clément de Loubens, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, 2017, 49 (3), pp.035501. ⟨10.1088/1873-7005/aa6270⟩. ⟨hal-02020111⟩ Plus de détails...
Soft microcapsules moving in a cylindrical capillary deform from quasi-spherical shapes to elongated shapes with an inversion of curvature at the rear. We investigated the perturbation of the flow by particle tracking velocimetry around deformed microcapsules in confined flow. These experiments are completed by numerical simulations. Microcapsules are made of a thin membrane of polymerized human albumin and their shear elastic moduli are previously characterized in a cross flow chamber. Firstly, the velocity of the microcapsule can be calculated by theoretical predictions for rigid spheres, even for large deformations as 'parachute-like' shapes, if a relevant definition of the ratio of confinement is chosen. Secondly, at the rear and the front of the microcapsule, the existence of multiple recirculation regions is governed by the local curvature of the membrane. The amplitudes of these perturbations increase with the microcapsule deformation, whereas their axial extents are comparable to the radius of the capillary whatever the confinement and the capillary number. We conclude that whereas the motion of microcapsules in confined flow has quantitative similitudes with rigid spheres in term of velocity and axial extent of the perturbation, their presence induces variations in the flow field that are related to the local deformation of the membrane as in droplets.
Jonathan Gubspun, Marc Georgelin, Julien Deschamps, Marc Leonetti, Clément de Loubens, et al.. Perturbations of the flow induced by a microcapsule in a capillary tube. Fluid Dynamics Research, 2017, 49 (3), pp.035501. ⟨10.1088/1873-7005/aa6270⟩. ⟨hal-02020111⟩
S. Bodjona, E. Videcoq, Richard Saurel, A. Chinnayya, A.M. Benselama, et al.. Transient simulation of a two-phase loop thermosyphon with a model out of thermodynamic equilibrium. International Journal of Heat and Mass Transfer, 2017, 108, pp.2321 - 2332. ⟨10.1016/j.ijheatmasstransfer.2017.01.061⟩. ⟨hal-01678307⟩ Plus de détails...
Numerical investigation of two-phase loop thermosyphon (2PLT) in steady and transient states is addressed. A one-dimensional two-phase flow model describing a liquid-gas mixture in both mechanical and thermal equilibrium but out of thermodynamic equilibrium is developed. The model considers subcooled liquid and over heated vapor as well as phase transition (evaporation and condensation). The flow model is solved with a specific hyperbolic solver based on Godunov method and Harten-Lax-van Leer-Contact (HLLC) Riemann solver. A parametric study on the thermal power at the evaporator is performed in steady and transient states, the aim being to determine the effects of thermal power increase at the evaporator on the loop behavior. The comparison between Goodwin and Stiffened Gas (SG) equation of state (EOS) models shows fair agreement for latent heat of vaporization, specific volume and enthalpy for both liquid and vapor phases. Simulation of four test cases, corresponding to different evaporator thermal loads, is also carried out in transient state showing that loop response is correctly reproduced by this numerical approach, novel in the context of thermosyphon loops.
S. Bodjona, E. Videcoq, Richard Saurel, A. Chinnayya, A.M. Benselama, et al.. Transient simulation of a two-phase loop thermosyphon with a model out of thermodynamic equilibrium. International Journal of Heat and Mass Transfer, 2017, 108, pp.2321 - 2332. ⟨10.1016/j.ijheatmasstransfer.2017.01.061⟩. ⟨hal-01678307⟩
Journal: International Journal of Heat and Mass Transfer
C. Pantano, Richard Saurel, T. Schmitt. An oscillation free shock-capturing method for compressible van der Waals supercritical fluid flows. Journal of Computational Physics, 2017, 335, pp.780 - 811. ⟨10.1016/j.jcp.2017.01.057⟩. ⟨hal-01678279⟩ Plus de détails...
Numerical solutions of the Euler equations using real gas equations of state (EOS) often exhibit serious inaccuracies. The focus here is the van der Waals EOS and its variants (often used in supercritical fluid computations). The problems are not related to a lack of convexity of the EOS since the EOS are considered in their domain of convexity at any mesh point and at any time. The difficulties appear as soon as a density discontinuity is present with the rest of the fluid in mechanical equilibrium and typically result in spurious pressure and velocity oscillations. This is reminiscent of well-known pressure oscillations occurring with ideal gas mixtures when a mass fraction discontinuity is present, which can be interpreted as a discontinuity in the EOS parameters. We are concerned with pressure oscillations that appear just for a single fluid each time a density discontinuity is present. The combination of density in a nonlinear fashion in the EOS with diffusion by the numerical method results in violation of mechanical equilibrium conditions which are not easy to eliminate, even under grid refinement. A cure to this problem is developed in the present paper for the van der Waals EOS based on previous ideas. A special extra field and its corresponding evolution equation is added to the flow model. This new field separates the evolution of the nonlinear part of the density in the EOS and produce oscillation free solutions. The extra equation being nonconservative the behavior of two established numerical schemes on shocks computation is studied and compared to exact reference solutions that are available in the present context. The analysis shows that shock conditions of the nonconservative equation have important consequence on the results. Last, multidimensional computations of a supercritical gas jet is performed to illustrate the benefits of the present method, compared to conventional flow solvers.
C. Pantano, Richard Saurel, T. Schmitt. An oscillation free shock-capturing method for compressible van der Waals supercritical fluid flows. Journal of Computational Physics, 2017, 335, pp.780 - 811. ⟨10.1016/j.jcp.2017.01.057⟩. ⟨hal-01678279⟩
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩ Plus de détails...
An accurate 2-D numerical model that accounts for concentration polarization and osmotic effects is developed for the cross-flow filtration in a membrane channel. Focused on the coupling between laminar hydrodynam-ics and mass transfer, the numerical approach solves the solute conservation equation together with the steady Navier-Stokes equations under the Prandtl approximation, which offers a simplified framework to enforce the non-linear coupling between filtration and concentration polarization at the membrane surface. The present approach is first validated thanks to the comparison with classical exact analytical solutions for hydrodynamics and/or mass transfer, as well as with approximated analytical solutions that attempted at coupling the various phenomena. The effects of the main parameters in cross-flow reverse osmosis (RO) or nanofiltration (NF) (feed concentration, axial flow rate, operating pressure and membrane permeability) on streamlines, velocity profile, longitudinal pressure drop, local permeate flux and solute concentration profile are predicted with the present numerical model, and discussed. With the use of data reported from NF and RO experiments, the Prandtl approximation model is shown to accurately correlate both average permeate flux and local solute concentration over a wide range of operating conditions.
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Darrieus–Landau instability of premixed flames enhanced by fuel droplets. Combustion Theory and Modelling, 2017, 21 (4), pp.630 - 645. ⟨10.1080/13647830.2017.1279756⟩. ⟨hal-01678255⟩ Plus de détails...
Recent experiments on spray flames propagating in a Wilson cloud chamber have established that spray flames are much more sensitive to wrinkles or corrugations than single-phase flames. To propose certain elements of explanation, we numerically study the Darrieus–Landau (or hydrodynamic) instability (DL-instability) developing in premixtures that contain an array of fuel droplets. Two approaches are compared: numerical simulation starting from the general conservation laws in reactive media, and the numerical computation of Sivashinsky-type model equations for DL-instability. Both approaches provide us with results in deep agreement. It is first shown that the presence of droplets in fuel–air premixtures induces initial perturbations which are large enough to trigger the DL-instability. Second, the droplets are responsible for additional wrinkles when the DL-instability is developed. The latter wrinkles are of length scales shorter than those of the DL-instability, in such a way that the DL-unstable spray flames have a larger front surface and therefore propagate faster than the single-phase ones when subjected to the same instability
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Darrieus–Landau instability of premixed flames enhanced by fuel droplets. Combustion Theory and Modelling, 2017, 21 (4), pp.630 - 645. ⟨10.1080/13647830.2017.1279756⟩. ⟨hal-01678255⟩
H Berjamin, N Favrie, B Lombard, G Chiavassa. Nonlinear waves in solids with slow dynamics: an internal-variable model. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017, 473 (2201), pp.20170024. ⟨10.1098/rspa.2017.0024⟩. ⟨hal-01517335⟩ Plus de détails...
In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease known as " slow dynamics " occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. is based on a variable that describes the softening of the material [Phys. Rev. E 70-1, 2004]. However, this model is 1D and it is not thermodynamically admissible. In the present article, a 3D model is derived in the framework of the finite strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitu-tive law is deduced from the Clausius-Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of continuum is thermodynamically admissible and dissipative (inelas-tic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments.
H Berjamin, N Favrie, B Lombard, G Chiavassa. Nonlinear waves in solids with slow dynamics: an internal-variable model. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2017, 473 (2201), pp.20170024. ⟨10.1098/rspa.2017.0024⟩. ⟨hal-01517335⟩
Journal: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Pierre Boivin, A.L. Sánchez, F.A. Williams. Analytical prediction of syngas induction times. Combustion and Flame, 2017, 176, pp.489 - 499. ⟨10.1016/j.combustflame.2016.11.008⟩. ⟨hal-01417104⟩ Plus de détails...
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple phase transition relaxation solver for liquid-vapor flows. International Journal for Numerical Methods in Fluids, 2017, 83 (7), pp.583-605. ⟨10.1002/fld.4282⟩. ⟨hal-01359203⟩ Plus de détails...
Determining liquid-vapor phase equilibrium is often required in multiphase flow computations. Existing equilibrium solvers are either accurate but computationally expensive, or cheap but inaccurate. The present paper aims at building a fast and accurate specific phase equilibrium solver, specifically devoted to unsteady multiphase flow computations. Moreover, the solver is efficient at phase diagram bounds, where non-equilibrium pure liquid and pure gas are present. It is systematically validated against solutions based on an accurate (but expensive) solver. Its capability to deal with cavitating, evaporating and condensing two-phase flows is highlighted on severe test problems both 1D and 2D.
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple phase transition relaxation solver for liquid-vapor flows. International Journal for Numerical Methods in Fluids, 2017, 83 (7), pp.583-605. ⟨10.1002/fld.4282⟩. ⟨hal-01359203⟩
Journal: International Journal for Numerical Methods in Fluids
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple and fast phase transition relaxation solver for compressible multicomponent two-phase flows. Computers and Fluids, 2017, 150, pp.31 - 45. ⟨10.1016/j.compfluid.2017.03.022⟩. ⟨hal-01502389⟩ Plus de détails...
The present paper aims at building a fast and accurate phase transition solver dedicated to unsteady multiphase flow computations. In a previous contribution (Chiapolino et al. 2017), such a solver was successfully developed to compute thermodynamic equilibrium between a liquid phase and its corresponding vapor phase. The present work extends the solver's range of application by considering a multicomponent gas phase instead of pure vapor, a necessary improvement in most practical applications. The solver proves easy to implement compared to common iterative procedures, and allows systematic CPU savings over 50%, at no cost in terms of accuracy. It is validated against solutions based on an accurate but expensive iterative solver. Its capability to deal with cavitating, evaporating and condensing two-phase flows is highlighted on severe test problems both 1D and 2D.
Alexandre Chiapolino, Pierre Boivin, Richard Saurel. A simple and fast phase transition relaxation solver for compressible multicomponent two-phase flows. Computers and Fluids, 2017, 150, pp.31 - 45. ⟨10.1016/j.compfluid.2017.03.022⟩. ⟨hal-01502389⟩
H Berjamin, Bruno Lombard, Guillaume Chiavassa, N Favrie. Analytical solution to the 1D nonlinear elastodynamics with general constitutive laws. Wave Motion, 2017, 74, pp.35-55. ⟨10.1016/j.wavemoti.2017.06.006⟩. ⟨hal-01350116⟩ Plus de détails...
Under the hypothesis of small deformations, the equations of 1D elastodynamics write as a 2 × 2 hyperbolic system of conservation laws. Here, we study the Riemann problem for convex and nonconvex constitutive laws. In the convex case, the solution can include shock waves or rarefaction waves. In the nonconvex case, compound waves must also be considered. In both convex and nonconvex cases, a new existence criterion for the initial velocity jump is obtained. Also, admissibility regions are determined. Lastly, analytical solutions are completely detailed for various constitutive laws (hyperbola, tanh and polynomial), and reference test cases are proposed.
H Berjamin, Bruno Lombard, Guillaume Chiavassa, N Favrie. Analytical solution to the 1D nonlinear elastodynamics with general constitutive laws. Wave Motion, 2017, 74, pp.35-55. ⟨10.1016/j.wavemoti.2017.06.006⟩. ⟨hal-01350116⟩
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩ Plus de détails...
Stockpiles of organic porous materials such as biosolids, coal, compost and woodchips are susceptible to spontaneous combustion. Flow fields within such materials are induced by buoyant forces and external agents such as the wind. However, the external forces may vary on a time scale of seconds, whereas the heat, mass and momentum processes within the porous medium may occur over timescales days or months. It would be computationally prohibitive to resolve all of the timescales, hence in this paper mean external forces are coupled to the flow field within stockpiles of biosolids by means of a penalisation method. It has been determined that four variables have a profound influence of the flow fields within porous media. These are the velocity of the wind, the permeability of the porous biosolids, the angle of repose of the medium and aspect ratio of the stockpile. Four distinct flow regimes within the stockpiles have been identified. A correlation has been developed to assist managers of stockpiles, which relates mean velocities within the four flow regimes with a Darcy and Reynolds number, the aspect ratio and angle of repose. The correlation is accurate for two of the four flow regions identified, but the error in predicting the two remaining regions is relatively large. However, this error is expected to have minimal impact on estimating the time for spontaneous combustion to occur.
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩
Journal: International Journal of Heat and Fluid Flow
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small−scale waves within the Stewartson layers of the thermally driven rotating annulus
. Journal of Fluid Mechanics, In press. ⟨hal-01670784⟩ Plus de détails...
Thomas von Larcher, Stéphane Viazzo, Uwe Harlander, Miklos Vincze, Anthony Randriamampianina. Instabilities and small−scale waves within the Stewartson layers of the thermally driven rotating annulus
. Journal of Fluid Mechanics, In press. ⟨hal-01670784⟩
Romain Thimothée, Christian Chauveau, Fabien Halter, Colette Nicoli, Pierre Haldenwang, et al.. Microgravity experiments and numerical studies on ethanol/air spray flames. Comptes Rendus. Mécanique, 2017, 345 (2), pp.99 - 116. ⟨10.1016/j.crme.2016.10.013⟩. ⟨hal-01441677⟩ Plus de détails...
Spray flames are known to exhibit amazing features in comparison with single-phase flames. The weightless situation offers the conditions in which the spray characteristics can be well controlled before and during combustion. The article reports on a joint experimental/numerical work that concerns ethanol/air spray flames observed in a spherical chamber using the condensation technique of expansion cooling (based on the Wilson cloud chamber principle), under microgravity. We describe the experimental setup and give details on the creation of a homogeneous and nearly monosized aerosol. Different optical diagnostics are employed successfully to measure the relevant parameters of two-phase combustion. A classical shadowgraphy system is used to track the flame speed propagation and allow us to observe the flame front instability. The complete characterization of the aerosol is performed with a laser diffraction particle size analyser by measuring the droplet diameter and the droplet density number, just before ignition. A laser tomography device allows us to measure the temporal evolution of the droplet displacement during flame propagation, as well as to identify the presence of droplets in the burnt gases. The numerical modelling is briefly recalled. In particular, spray-flame propagation is schematized by the combustion spread in a 2-D lattice of fuel droplets surrounded by an initial gaseous mixture of fuel vapour and air. In its spherical expansion, the spray flame presents a corrugated front pattern, while the equivalent single-phase flame does not. From a numerical point of view, the same phenomena of wrinkles are also observed in the simulations. The front pattern pointed out by the numerical approach is identified as of Darrieus–Landau (DL) type. The droplets are found to trigger the instability. Then, we quantitatively compare experimental data with numerical predictions on spray-flame speed. The experimental results show that the spray-flame speed is of the same order of magnitude as that of the single-phase premixed flame. On the other hand, the numerical results exhibit the role played by the droplet radius in spray-flame propagation, and retrieve the experiments only when the droplets are small enough and when the Darrieus–Landau instability is triggered. A final discussion is developed to interpret the various patterns experimentally observed for the spray-flame front.
Romain Thimothée, Christian Chauveau, Fabien Halter, Colette Nicoli, Pierre Haldenwang, et al.. Microgravity experiments and numerical studies on ethanol/air spray flames. Comptes Rendus. Mécanique, 2017, 345 (2), pp.99 - 116. ⟨10.1016/j.crme.2016.10.013⟩. ⟨hal-01441677⟩
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩ Plus de détails...
A flow model is derived for the numerical simulation of interfacial flows with phase transition. The model arises from the classical multi-component Euler equations, but is associated to a non-classical thermodynamic closure: each phase is compressible and evolves in its own subvolume, with phases sharing common pressure, velocity and temperature, leading to non-trivial thermodynamic relations for the mixture. Phase transition is made possible through the introduction of Gibbs free energy relaxation terms in the equations. Capillary effects and heat conduction—essential in boiling flows—are introduced as well. The resulting multi-phase flow model is hyperbolic, valid for arbitrary density jumps at interfaces as well as arbitrary flow speeds. Its capabilities are illustrated successively through examples of nozzle induced cavitation and heated wall induced boiling.
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩ Plus de détails...
Stockpiles of organic porous materials such as biosolids, coal, compost and woodchips are susceptible to spontaneous combustion. Flow fields within such materials are induced by buoyant forces and external agents such as the wind. However, the external forces may vary on a time scale of seconds, whereas the heat, mass and momentum processes within the porous medium may occur over timescales days or months. It would be computationally prohibitive to resolve all of the timescales, hence in this paper mean external forces are coupled to the flow field within stockpiles of biosolids by means of a penalisation method. It has been determined that four variables have a profound influence of the flow fields within porous media. These are the velocity of the wind, the permeability of the porous biosolids, the angle of repose of the medium and aspect ratio of the stockpile. Four distinct flow regimes within the stockpiles have been identified. A correlation has been developed to assist managers of stockpiles, which relates mean velocities within the four flow regimes with a Darcy and Reynolds number, the aspect ratio and angle of repose. The correlation is accurate for two of the four flow regions identified, but the error in predicting the two remaining regions is relatively large. However, this error is expected to have minimal impact on estimating the time for spontaneous combustion to occur.
Rachel Aganetti, Aymeric Lamorlette, G.R. Thorpe. The relationship between external and internal flow in a porous body using the penalisation method. International Journal of Heat and Fluid Flow, 2017, 66 (66), pp.185 - 196. ⟨10.1016/j.ijheatfluidflow.2017.06.003⟩. ⟨hal-01547073⟩
Journal: International Journal of Heat and Fluid Flow
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩ Plus de détails...
A flow model is derived for the numerical simulation of interfacial flows with phase transition. The model arises from the classical multi-component Euler equations, but is associated to a non-classical thermodynamic closure: each phase is compressible and evolves in its own subvolume, with phases sharing common pressure, velocity and temperature, leading to non-trivial thermodynamic relations for the mixture. Phase transition is made possible through the introduction of Gibbs free energy relaxation terms in the equations. Capillary effects and heat conduction—essential in boiling flows—are introduced as well. The resulting multi-phase flow model is hyperbolic, valid for arbitrary density jumps at interfaces as well as arbitrary flow speeds. Its capabilities are illustrated successively through examples of nozzle induced cavitation and heated wall induced boiling.
Richard Saurel, Olivier Le Métayer, Pierre Boivin. From Cavitating to Boiling Flows. d'Agostino L., Salvetti M.; CISM International Centre for Mechanical Sciences (Courses and Lectures). Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines , 575, Springer pp.259-282 2017, 978-3-319-49717-4. ⟨hal-01678361⟩
Manel Wannassi, Isabelle Raspo. Numerical study of non-isothermal adsorption of Naphthalene in supercritical CO2: behavior near critical point. Journal of Supercritical Fluids, 2016, 117, pp.203-218. ⟨10.1016/j.supflu.2016.06.020⟩. ⟨hal-01369830⟩ Plus de détails...
In this study, adsorption in a model binary mixture is investigated near the critical point in a side-heated cavity. The diverging behavior of the equilibrium constant and the Piston effect are taken into account and their influence on the adsorption process is pointed to. The modeling is based on numerical integration of the differential equations, considering the Navier-Stokes equations coupled with the energy and mass diffusion balances. By means of this model, the temperature, density and adsorbed concentration profiles are drawn at different times. Some fundamental concepts about the system’s response to the heating are illustrated. The results reveal that the adsorption process is influenced by the combined effect of several parameters, such as the gravity and the proximity to the critical point. In particular, the adsorbed amount exhibits a reversed dependency on the wall heating very close to the critical point, which confirms the complexity of such a process in binary systems near critical conditions.
Manel Wannassi, Isabelle Raspo. Numerical study of non-isothermal adsorption of Naphthalene in supercritical CO2: behavior near critical point. Journal of Supercritical Fluids, 2016, 117, pp.203-218. ⟨10.1016/j.supflu.2016.06.020⟩. ⟨hal-01369830⟩
Evelyne Neau, Isabelle Raspo, Joan Escandell. The NRTL-PRA group contribution EoS for the simultaneous prediction of LLE, VLE and hE of hydrocarbon mixtures with associating compounds. Fluid Phase Equilibria, 2016, 427, pp.126-142. ⟨10.1016/j.fluid.2016.06.035⟩. ⟨hal-01369874⟩ Plus de détails...
The goal of this study is to propose a modification of the NRTL-PR EoS for the prediction of phase equilibria and excess enthalpies in mixtures containing methanol with hydrocarbons; indeed, with these systems, the original equation is confronted to many difficulties arising from the simultaneous prediction of liquid-liquid equilibria together with vapor-liquid and enthalpy data. For this purpose, an additional term is included in the EoS excess Gibbs energy, , of the Peng-Robinson equation to account for the self-association of methanol. The resulting NRTL-PRA EoS is successfully used for the prediction of both liquid-liquid and vapor-liquid equilibria, as well as excess enthalpies, in mixtures of methanol with hydrocarbons, light gases and associating compounds. Results are comparable to those obtained with other predictive EoS (VTPR and SAFT), but with the main advantage to predict all thermodynamic properties with a simple cubic equation.
Evelyne Neau, Isabelle Raspo, Joan Escandell. The NRTL-PRA group contribution EoS for the simultaneous prediction of LLE, VLE and hE of hydrocarbon mixtures with associating compounds. Fluid Phase Equilibria, 2016, 427, pp.126-142. ⟨10.1016/j.fluid.2016.06.035⟩. ⟨hal-01369874⟩
Romain Oguic, Sébastien Poncet, Stéphane Viazzo. High-order direct numerical simulations of a turbulent round impinging jet onto a rotating heated disk in a highly confined cavity. International Journal of Heat and Fluid Flow, 2016, 61 (B), pp.366-378. ⟨10.1016/j.ijheatfluidflow.2016.05.013⟩. ⟨hal-01461786⟩ Plus de détails...
The present work reports Direct Numerical Simulations (DNS) of an impinging round jet onto a rotating heated disk in a confined rotor-stator cavity. The geometrical characteristics of the system correspond to the experimental set-up developed by u. Pelle and S. Harmand. Heat transfer study in a rotor-stator system air-gap with an axial inflow. Applied Thermal Engineering, 29:1532-1543, 2009.]. The aspect ratio of the cavity G = h/R-d between the interdisk spacing h and the rotor radius R-d is fixed to 0.02 corresponding to a narrow-gap cavity. The axial Reynolds number Red based on the jet characteristics is also fixed to Re-j = 5300, while the rotational Reynolds number Re-Omega may vary to preserve the swirl parameter N proportional to Re(Omega)dRe(j) (0 <= N <= 2.47) between the present simulations and the experimental data of [J. Pelle and S. Harmand. Heat transfer study in a rotor-stator system air-gap with an axial inflow. Applied Thermal Engineering, 29:1532-1543, 2009.] and [T. D. Nguyen, J. Pelle, S. Harmand, and S. Poncet. PIV measurements of an air jet impinging on an open rotor-stator system. Experiments in Fluids, 53:401-412, 2012.] for comparisons. The results are discussed in terms of radial distributions of the mean velocity components and corresponding Reynolds stress tensor components. The swirl parameter does not modify the size of the recirculation bubble developed along the stator close to the pipe exit. For N >= 1.237, centrifugal effects at the rotor periphery are balanced by a centripetal flow along the stator. Some spiral patterns develop then in the stator boundary layer corresponding to the SRIII instability of [L. Schouveiler, P. Le Gal, and M. P. Chauve. Instabilities of the flow between a rotating and a stationary disk. Journal of Fluid Mechanics, 443:329-350, 2001.] in an enclosed cavity. The numerical results are found to agree particularly well with the experimental data in terms of the distribution of the local Nusselt number along the rotor. Finally, a correlation for its averaged value is proposed according to the swirl parameter. (C) 2016 Elsevier Inc. All rights reserved.
Romain Oguic, Sébastien Poncet, Stéphane Viazzo. High-order direct numerical simulations of a turbulent round impinging jet onto a rotating heated disk in a highly confined cavity. International Journal of Heat and Fluid Flow, 2016, 61 (B), pp.366-378. ⟨10.1016/j.ijheatfluidflow.2016.05.013⟩. ⟨hal-01461786⟩
Journal: International Journal of Heat and Fluid Flow
Salim Bounoua, Séverine Tomas, Jérôme Labille, Bruno Molle, Jacques Granier, et al.. Understanding physical clogging in drip irrigation: in situ, in-lab and numerical approaches. Irrigation Science, 2016, 34 (4), pp.327-342. ⟨10.1007/s00271-016-0506-8⟩. ⟨hal-01519534⟩ Plus de détails...
Dripper clogging is a major drawback of microirrigation systems that must be addressed to improve their efficiency and durability. Particle-induced clogging is first studied in situ. The experiments consist in observing in real conditions the behavior of a series of drippers fitted on an agricultural plot in the south of France. The plot is supplied from a canal with Durance River water. The latter is loaded with sediments that gradually clog drippers and filters. Water analysis reveal that physicochemical clogging prevails over biological clogging. This characterization helps in setting in-lab experiment protocol. Indeed, besides field observation of clogging, laboratory analyses of both the irrigation water and the clogging material are performed with reactive and inert clay: smectite and an illite-calcite mix. A surprising tendency is observed: Salt concentration in smectite seeded water decreases the clogging, whereas it increases agglomerate size. Computational fluid dynamic simulations are carried out to investigate the impact of particles on flow behavior. Results demonstrate that clay particles interacting with the flow govern the complex structure of the fluid velocity fields inside the dripper labyrinth channel.
Salim Bounoua, Séverine Tomas, Jérôme Labille, Bruno Molle, Jacques Granier, et al.. Understanding physical clogging in drip irrigation: in situ, in-lab and numerical approaches. Irrigation Science, 2016, 34 (4), pp.327-342. ⟨10.1007/s00271-016-0506-8⟩. ⟨hal-01519534⟩
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩ Plus de détails...
A novel experimental method and its associated model are proposed for the simultaneous determination of membrane solute and solvent permeabilities, which are essential transport parameters of reverse osmosis models used for process simulation. The method utilizes a single bench-scale batch apparatus consisting of two stirred half-cells containing solutions of different concentrations separated by a membrane across which coupled non-steady-state solute diffusion and solvent osmosis take place countercurrently in the absence of transmembrane pressure difference. Results are presented from days-long determinations of the water and sodium chloride permeabilities of Filmtec BW30 and NF270 membrane samples for initial transmembrane salt concentration differences ranging from 1 g L-1 to 35 g L-1. When used as input parameters for the simulation of pilot reverse osmosis desalination tests, the osmotic-diffusive salt permeabilities approximated the experimental rejection rates.
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩
Richard Saurel, Pierre Boivin, Olivier Le Métayer. A general formulation for cavitating, boiling and evaporating flows. Computers and Fluids, 2016, 128, pp.53-64. ⟨10.1016/j.compfluid.2016.01.004⟩. ⟨hal-01277179⟩ Plus de détails...
A flow model is derived for the numerical simulation of multi-phase flows with phase transition. The model arises from the classical multi-component Euler equations, but is associated to a non-classical thermodynamic closure: each phase is compressible and evolves in its own subvolume, with phases sharing common pressure, velocity and temperature, leading to non-trivial thermodynamic relations for the mixture. Phase transition is made possible through the introduction of Gibbs free energy relaxation terms in the equations. Capillary effects and heat conduction – essential in boiling flows – are introduced as well. The resulting multi-phase flow model is hyperbolic, valid for arbitrary density jumps at interfaces as well as arbitrary flow speeds. Its capabilities are illustrated successively through examples of nozzle induced cavitation, a high-speed evaporating liquid jet, and heated wall induced boiling.
Richard Saurel, Pierre Boivin, Olivier Le Métayer. A general formulation for cavitating, boiling and evaporating flows. Computers and Fluids, 2016, 128, pp.53-64. ⟨10.1016/j.compfluid.2016.01.004⟩. ⟨hal-01277179⟩
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Spray-Flame Dynamics in a Rich Droplet Array. Flow, Turbulence and Combustion, 2016, 96 (2), pp.377-389. ⟨10.1007/s10494-015-9675-4⟩. ⟨hal-01282878⟩ Plus de détails...
In a recent numerical paper (Nicoli et al. Combust. Sci. Technol. vol. 186, pp. 103-119; 2014) [1], a model of isobaric flame propagation in lean sprays has been proposed. The initial state of the monodisperse mists was schematized by a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a saturated mixture of alkane and air. In the present study, the previous model is complemented with an original chemical scheme that allows us to study the combustion of rich alkane/air mixtures.
Colette Nicoli, Pierre Haldenwang, Bruno Denet. Spray-Flame Dynamics in a Rich Droplet Array. Flow, Turbulence and Combustion, 2016, 96 (2), pp.377-389. ⟨10.1007/s10494-015-9675-4⟩. ⟨hal-01282878⟩
Rachael Aganetti, Aymeric Lamorlette, Guilbert Emilie, Dominique Morvan, G.R. Thorpe. Advection and the self-heating of organic porous media. International Journal of Heat and Mass Transfer, 2016, ⟨10.1016/j.ijheatmasstransfer.2015.11.023⟩. ⟨hal-01345737⟩ Plus de détails...
Self-heating is commonly observed when organic materials such as biosolids, coal, food grains and compost are stockpiled. A convection–diffusion model is presented that accounts for the roles of advection and the transport of oxygen in the self-heating process, as well as the development of an empirical correlation between dimensionless Darcy number, Frank–Kamenetskii parameter and pile aspect ratio, to predict the critical permeability above which thermal runaway can be avoided. It is apparent that the permeability of the stockpile determines the likelihood of the thermal runaway. However, the solids that form a stockpile are poly-disperse and it is essential to determine an effective permeability. This has been achieved using experimental data on biosolids obtained from a wastewater treatment plant in Australia. With this method the model is used to demonstrate how the permeability of a stockpile might be adjusted to reduce the incidence of thermal runaway.
Rachael Aganetti, Aymeric Lamorlette, Guilbert Emilie, Dominique Morvan, G.R. Thorpe. Advection and the self-heating of organic porous media. International Journal of Heat and Mass Transfer, 2016, ⟨10.1016/j.ijheatmasstransfer.2015.11.023⟩. ⟨hal-01345737⟩
Journal: International Journal of Heat and Mass Transfer
O Le Métayer, Richard Saurel. The Noble-Abel Stiffened-Gas equation of state. Physics of Fluids, 2016, 28, pp.046102. ⟨10.1063/1.4945981⟩. ⟨hal-01305974⟩ Plus de détails...
Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hy-perbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate , this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named 'Noble Abel Stiffened Gas' (NASG), this formulation being a significant improvement of the popular 'Stiffened Gas' (SG) EOS. It is a combination of the so-called 'Noble-Abel' and 'Stiffened Gas' equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.
O Le Métayer, Richard Saurel. The Noble-Abel Stiffened-Gas equation of state. Physics of Fluids, 2016, 28, pp.046102. ⟨10.1063/1.4945981⟩. ⟨hal-01305974⟩
Mohamad El Houssami, J.C. Thomas, Aymeric Lamorlette, Dominique Morvan, M. Chaos, et al.. Experimental and numerical studies characterizing the burning dynamics of wildland fuels. Combustion and Flame, 2016, 168, pp.113-126. ⟨10.1016/j.combustflame.2016.04.004⟩. ⟨hal-01345741⟩ Plus de détails...
A method to accurately understand the processes controlling the burning behavior of porous wildland fuels is presented using numerical simulations and laboratory experiments. A multiphase approach has been implemented in OpenFOAM, which is based on the FireFOAM solver for large eddy simulations (LES). Conservation equations are averaged in a control volume containing a gas and a solid phase. Drying, pyrolysis, and char oxidation are described by interaction between the two phases. Numerical simulations are compared to laboratory experiments carried out with porous pine needle beds in the FM Global Fire Propagation Apparatus (FPA). These experiments are used to support the use and the development of submodels that represent heat transfer, pyrolysis, gas-phase combustion, and smoldering processes. The model is tested for different bulk densities, two distinct species and two different radiative heat fluxes used to heat up the samples. It has been possible to reproduce mass loss rates, heat release rates, and temperatures that agree with experimental observations, and to highlight the current limitations of the model.
Mohamad El Houssami, J.C. Thomas, Aymeric Lamorlette, Dominique Morvan, M. Chaos, et al.. Experimental and numerical studies characterizing the burning dynamics of wildland fuels. Combustion and Flame, 2016, 168, pp.113-126. ⟨10.1016/j.combustflame.2016.04.004⟩. ⟨hal-01345741⟩
Damien Furfaro, Richard Saurel. Modeling droplet phase change in the presence of a multi-component gas mixture. Computational & Applied Mathematics, 2016, 272 (part.2), pp.518-541. ⟨10.1016/j.amc.2015.02.083⟩. ⟨hal-01278890⟩ Plus de détails...
Dispersed liquid droplet flows with evaporation and condensation in multi-component gas mixture made of vapor and other gas phase chemical species such as air occur in many engineering applications dealing with two-phase flows. However, existing models are essentially derived for vaporization occurring in sprays combustion. It means that the energy is transferred from a hot gas to the liquid to produce its phase change. This is thus a non-symmetric approach as in some situations the energy is already stored in the liquid phase and flashing occurs as a consequence of pressure drop. In the present paper a droplet mass transfer model is derived and is valid in any situation: evaporation, flashing and condensation. It accounts for: - coupled heat and mass diffusion in the gas phase, - thermodynamics of the multi-component gas mixture, - heat diffusion inside the liquid droplet, enabling consideration of both droplet heating and cooling. These effects are important in evaporating and flashing situations respectively. The resulting model consists in an algebraic non-linear system of three equations giving the interface temperature, the mass flow rate and vapor species concentration at the interface. These interfacial variables enable computation of the mass species, momentum and energy transfer rates appearing in volume averaged two-phase flow models. Computational examples are shown with this mass transfer model embedded in a compressible two-phase flow model of Baer and Nunziato (1986) type.
Damien Furfaro, Richard Saurel. Modeling droplet phase change in the presence of a multi-component gas mixture. Computational & Applied Mathematics, 2016, 272 (part.2), pp.518-541. ⟨10.1016/j.amc.2015.02.083⟩. ⟨hal-01278890⟩
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Rich Spray-Flame Propagating through a 2D-Lattice of Alkane Droplets in Air. Combustion and Flame, 2015, 162 (12), pp.4598-4611. ⟨10.1016/j.combustflame.2015.09.018⟩. ⟨hal-01255816⟩ Plus de détails...
In a recent numerical paper (Nicoli et al. Combust. Sci. Technol. vol. 186, pp. 103-119; 2014) [1], a model of isobaric flame propagation in lean sprays has been proposed. The initial state of the monodisperse mists was schematized by a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a saturated mixture of alkane and air. In the present study, the previous model is complemented with an original chemical scheme that allows us to study the combustion of rich alkane/air mixtures.
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Rich Spray-Flame Propagating through a 2D-Lattice of Alkane Droplets in Air. Combustion and Flame, 2015, 162 (12), pp.4598-4611. ⟨10.1016/j.combustflame.2015.09.018⟩. ⟨hal-01255816⟩
Anthony Randriamampianina, Emilia Crespo del Arco. Inertia–gravity waves in a liquid-filled, differentially heated, rotating annulus. Journal of Fluid Mechanics, 2015, 782, pp.144- 177. ⟨10.1017/jfm.2015.522⟩. ⟨hal-01230540⟩ Plus de détails...
Direct numerical simulations based on high-resolution pseudospectral methods are carried out for detailed investigation into the instabilities arising in a differentially heated, rotating annulus, the baroclinic cavity. Following previous works using air (Randriamampianina et al., J. Fluid Mech., vol. 561, 2006, pp. 359–389), a liquid defined by Prandtl number Pr=16 is considered in order to better understand, via the Prandtl number, the effects of fluid properties on the onset of gravity waves. The computations are particularly aimed at identifying and characterizing the spontaneously emitted small-scale fluctuations occurring simultaneously with the baroclinic waves. These features have been observed as soon as the baroclinic instability sets in. A three-term decomposition is introduced to isolate the fluctuation field from the large-scale baroclinic waves and the time-averaged mean flow. Even though these fluctuations are found to propagate as packets, they remain attached to the background baroclinic waves, locally triggering spatio-temporal chaos, a behaviour not observed with the air-filled cavity. The properties of these features are analysed and discussed in the context of linear theory. Based on the Richardson number criterion, the characteristics of the generation mechanism are consistent with a localized instability of the shear zonal flow, invoking resonant over-reflection.
Anthony Randriamampianina, Emilia Crespo del Arco. Inertia–gravity waves in a liquid-filled, differentially heated, rotating annulus. Journal of Fluid Mechanics, 2015, 782, pp.144- 177. ⟨10.1017/jfm.2015.522⟩. ⟨hal-01230540⟩
Romain Oguic, Stéphane Viazzo, Sébastien Poncet. A parallelized multidomain compact solver for incompressible turbulent flows in cylindrical geometries. Journal of Computational Physics, 2015, 300, pp.710-731. ⟨10.1016/j.jcp.2015.08.003⟩. ⟨hal-01299082⟩ Plus de détails...
We present an efficient parallelized multidomain algorithm for solving the 3D Navier–Stokes equations in cylindrical geometries. The numerical method is based on fourth-order compact schemes in the two non-homogeneous directions and Fourier series expansion in the azimuthal direction. The temporal scheme is a second-order semi-implicit projection scheme leading to the solution of five Helmholtz/Poisson equations. To handle the singularity appearing at the axis in cylindrical coordinates, while being able to have a thinner or conversely a coarser mesh in this zone, parity conditions are imposed at r=0r=0 for each flow variable and azimuthal Fourier mode. To simulate flows in irregularly shaped cylindrical geometries and benefit from a hybrid OpenMP/MPI parallelization, an accurate perfectly free-divergence multidomain method based on the influence matrix technique is proposed. First, the accuracy of the present solver is checked by comparison with analytical solutions and the scalability is then evaluated. Simulations using the present code are then compared to reliable experimental and numerical results of the literature showing good quantitative agreements in the cases of the axisymmetric and 3D unsteady vortex breakdowns in a cylinder and turbulent pipe flow. Finally to show the capability of the algorithm to deal with more complex flows relevant of turbomachineries, the turbulent flow inside a simplified stage of High-Pressure compressor is considered.
Romain Oguic, Stéphane Viazzo, Sébastien Poncet. A parallelized multidomain compact solver for incompressible turbulent flows in cylindrical geometries. Journal of Computational Physics, 2015, 300, pp.710-731. ⟨10.1016/j.jcp.2015.08.003⟩. ⟨hal-01299082⟩
Guillaume Chiavassa, Maria Carmen Martí, Pep Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, 2015, 93 (11), pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩ Plus de détails...
Polydisperse sedimentation models can be described by a strongly coupled system of conservation laws for the concentration of each species of solids. Typical solutions for the sedimentation model considered for batch settling in a column include stationary kinematic shocks separating layers of sediment of different composition. This phenomenon, known as segregation of species, is a specially demanding task for numerical simulation due to the need of accurate numerical simulations. Very high-order accurate solutions can be constructed by incorporating characteristic information, available due to the hyperbolicity analysis made in Donat and Mulet [A secular equation for the Jacobian matrix of certain multispecies kinematic flow models, Numer. Methods Partial Differential Equations 26 (2010), pp. 159–175.] But characteristic-based schemes, see Bürger et al. [On the implementation of WENO schemes for a class of polydisperse sedimentation models, J. Comput. Phys. 230 (2011), pp. 2322–2344], are very expensive in terms of computational time, since characteristic information is not readily available, and they are not really necessary in constant areas, where a less complex method can obtain similar results. With this idea in mind, in this paper we develop a hybrid finite difference WENO scheme that only uses the characteristic information of the Jacobian matrix of the system in those regions where singularities exist or are starting to develop, while it uses a component-wise approximation of the scheme in smooth regions. We perform some experiments showing the computational gains that can be achieved by this strategy.
Guillaume Chiavassa, Maria Carmen Martí, Pep Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, 2015, 93 (11), pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩
Journal: International Journal of Computer Mathematics
Guillaume Chiavassa, Maria Carmen Martí, Pep Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, 2015, 93 (11), pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩ Plus de détails...
Polydisperse sedimentation models can be described by a strongly coupled system of conservation laws for the concentration of each species of solids. Typical solutions for the sedimentation model considered for batch settling in a column include stationary kinematic shocks separating layers of sediment of different composition. This phenomenon, known as segregation of species, is a specially demanding task for numerical simulation due to the need of accurate numerical simulations. Very high-order accurate solutions can be constructed by incorporating characteristic information, available due to the hyperbolicity analysis made in Donat and Mulet [A secular equation for the Jacobian matrix of certain multispecies kinematic flow models, Numer. Methods Partial Differential Equations 26 (2010), pp. 159–175.] But characteristic-based schemes, see Bürger et al. [On the implementation of WENO schemes for a class of polydisperse sedimentation models, J. Comput. Phys. 230 (2011), pp. 2322–2344], are very expensive in terms of computational time, since characteristic information is not readily available, and they are not really necessary in constant areas, where a less complex method can obtain similar results. With this idea in mind, in this paper we develop a hybrid finite difference WENO scheme that only uses the characteristic information of the Jacobian matrix of the system in those regions where singularities exist or are starting to develop, while it uses a component-wise approximation of the scheme in smooth regions. We perform some experiments showing the computational gains that can be achieved by this strategy.
Guillaume Chiavassa, Maria Carmen Martí, Pep Mulet. Hybrid WENO schemes for polydisperse sedimentation models. International Journal of Computer Mathematics, 2015, 93 (11), pp.1-17. ⟨10.1080/00207160.2015.1075985⟩. ⟨hal-01297719⟩
Journal: International Journal of Computer Mathematics
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩ Plus de détails...
The problem of a vesicle transported by a fluid flow can present a large range of length scales. One example is the case of a vesicle producing a tether, and eventually pearls, in an elongational flow. Another case occurs when a lubrication film is formed, such as during the short range interaction between two vesicles. Such problems are still challenging for 3D simulations. On the other hand, a good understanding could be obtained by first considering the axisymmetric regime when such a regime exists. An axisymmetric model could then be used, without the criticisms that can be made of a 2D approach. We propose such a model, primarily interested in flows through narrow cylindrical capillaries. Two options are compared, with and without explicit representation of the capillary boundaries by a mesh. The numerical effort is characterized as a function of the vesicle’s initial shape, the flow magnitude and the confinement. The model is able to treat typical configurations of red blood cells flowing through very narrow pores with extremely thin lubrication films.
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩ Plus de détails...
The problem of a vesicle transported by a fluid flow can present a large range of length scales. One example is the case of a vesicle producing a tether, and eventually pearls, in an elongational flow. Another case occurs when a lubrication film is formed, such as during the short range interaction between two vesicles. Such problems are still challenging for 3D simulations. On the other hand, a good understanding could be obtained by first considering the axisymmetric regime when such a regime exists. An axisymmetric model could then be used, without the criticisms that can be made of a 2D approach. We propose such a model, primarily interested in flows through narrow cylindrical capillaries. Two options are compared, with and without explicit representation of the capillary boundaries by a mesh. The numerical effort is characterized as a function of the vesicle’s initial shape, the flow magnitude and the confinement. The model is able to treat typical configurations of red blood cells flowing through very narrow pores with extremely thin lubrication films.
R. Trozzo, G. Boedec, M. Leonetti, M. Jaeger. Axisymmetric Boundary Element Method for vesicles in a capillary. Journal of Computational Physics, 2015, 289, pp.62-82. ⟨10.1016/j.jcp.2015.02.022⟩. ⟨hal-01281961⟩
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩ Plus de détails...
Motivated by the difficulties encountered by engineers to cool down the rotating shafts of industrial machines, the present work investigates the heat and mass transfers in the rotor-stator gap of a Taylor–Couette system with an axial water flow characterized by an aspect ratio Γ = 50 and a radius ratio η = 8/9. Extensive velocity and temperature measurements have been performed on an experimental set-up for a wide range of the flow parameters: the axial Reynolds number Re and the Taylor number Ta reach the values 1.12 × 104 and 7.9 × 107 respectively. In particular, coherent structures close to the rotating wall were measured by Stereo Particle Image Velocimetry. A correlation for the Nusselt number Nu on the rotating wall is finally provided against the axial Reynolds, Taylor and Prandtl numbers. Nu is proportional to the Taylor number to the power ∼0.13 close to the exponent 1/7 highlighted by an analytical model. This small exponent traduces the control of heat transfers by the rotating viscous layer and thus may explain the difficulty met by engineers to develop strategies for the effective cooling of such rotating apparatus.
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩
Journal: International Journal of Thermal Sciences
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩ Plus de détails...
Motivated by the difficulties encountered by engineers to cool down the rotating shafts of industrial machines, the present work investigates the heat and mass transfers in the rotor-stator gap of a Taylor–Couette system with an axial water flow characterized by an aspect ratio Γ = 50 and a radius ratio η = 8/9. Extensive velocity and temperature measurements have been performed on an experimental set-up for a wide range of the flow parameters: the axial Reynolds number Re and the Taylor number Ta reach the values 1.12 × 104 and 7.9 × 107 respectively. In particular, coherent structures close to the rotating wall were measured by Stereo Particle Image Velocimetry. A correlation for the Nusselt number Nu on the rotating wall is finally provided against the axial Reynolds, Taylor and Prandtl numbers. Nu is proportional to the Taylor number to the power ∼0.13 close to the exponent 1/7 highlighted by an analytical model. This small exponent traduces the control of heat transfers by the rotating viscous layer and thus may explain the difficulty met by engineers to develop strategies for the effective cooling of such rotating apparatus.
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩
Journal: International Journal of Thermal Sciences
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩ Plus de détails...
Motivated by the difficulties encountered by engineers to cool down the rotating shafts of industrial machines, the present work investigates the heat and mass transfers in the rotor-stator gap of a Taylor–Couette system with an axial water flow characterized by an aspect ratio Γ = 50 and a radius ratio η = 8/9. Extensive velocity and temperature measurements have been performed on an experimental set-up for a wide range of the flow parameters: the axial Reynolds number Re and the Taylor number Ta reach the values 1.12 × 104 and 7.9 × 107 respectively. In particular, coherent structures close to the rotating wall were measured by Stereo Particle Image Velocimetry. A correlation for the Nusselt number Nu on the rotating wall is finally provided against the axial Reynolds, Taylor and Prandtl numbers. Nu is proportional to the Taylor number to the power ∼0.13 close to the exponent 1/7 highlighted by an analytical model. This small exponent traduces the control of heat transfers by the rotating viscous layer and thus may explain the difficulty met by engineers to develop strategies for the effective cooling of such rotating apparatus.
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michael Le Bars. Velocity and temperature measurements in a turbulent water-filled Taylor–Couette–Poiseuille system. International Journal of Thermal Sciences, 2015, 90, pp.238-247. ⟨10.1016/j.ijthermalsci.2014.12.018⟩. ⟨hal-01308638⟩
Journal: International Journal of Thermal Sciences
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩ Plus de détails...
The performance of reverse osmosis and tight nanofiltration with flat-sheet membranes can be predicted accurately. The proposed numerical model solves the local momentum and mass conservation equations in the module's feed channel with solution-diffusion boundary conditions. Both qualitative and quantitative predictions of the permeate flux and of the rejection rate are obtained with an accuracy depending on the limitations of the solution-diffusion model for describing membrane mass transport and on the value of solute permeability. As an extension of the applications to plate-and-frame modules, the ability to describe the performance of processes carried out with spiral-wound modules is also tested with own desalination experiments and with data from the literature.
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩
Damien Furfaro, Richard Saurel. A simple HLLC-type Riemann solver for compressible non-equilibrium two-phase flows. Computers and Fluids, 2015, 111, pp.159-178. ⟨10.1016/j.compfluid.2015.01.016⟩. ⟨hal-01278892⟩ Plus de détails...
A simple, robust and accurate HLLC-type Riemann solver for two-phase 7-equation type models is built. It involves 4 waves per phase, i.e. the three conventional right- and left-facing and contact waves, augmented by an extra “interfacial” wave. Inspired by the Discrete Equations Method (Abgrall and Saurel, 2003), this wave speed (uIuI) is assumed function only of the piecewise constant initial data. Therefore it is computed easily from these initial states. The same is done for the interfacial pressure PIPI. Interfacial variables uIuI and PIPI are thus local constants in the Riemann problem. Thanks to this property there is no difficulty to express the non-conservative system of partial differential equations in local conservative form. With the conventional HLLC wave speed estimates and the extra interfacial speed uIuI, the four-waves Riemann problem for each phase is solved following the same strategy as in Toro et al. (1994) for the Euler equations. As uIuI and PIPI are functions only of the Riemann problem initial data, the two-phase Riemann problem consists in two independent Riemann problems with 4 waves only. Moreover, it is shown that these solvers are entropy producing. The method is easy to code and very robust. Its accuracy is validated against exact solutions as well as experimental data.
Damien Furfaro, Richard Saurel. A simple HLLC-type Riemann solver for compressible non-equilibrium two-phase flows. Computers and Fluids, 2015, 111, pp.159-178. ⟨10.1016/j.compfluid.2015.01.016⟩. ⟨hal-01278892⟩
Seyed Amin Ghaffari, Stéphane Viazzo, Kai Schneider, Patrick Bontoux. Simulation of forced deformable bodies interacting with two-dimensional incompressible flows: Application to fish-like swimming. International Journal of Heat and Fluid Flow, 2015, Theme special issue celebrating the 75th birthdays of Brian Launder and Kemo Hanjalic, 51, pp.88-109. ⟨10.1016/j.ijheatfluidflow.2014.10.023⟩. ⟨hal-00967077v2⟩ Plus de détails...
We present an efficient algorithm for simulation of deformable bodies interacting with two-dimensional incompressible flows. The temporal and spatial discretizations of the Navier-Stokes equations in vorticity stream-function formulation are based on classical fourth-order Runge-Kutta and compact finite differences, respectively. Using a uniform Cartesian grid we benefit from the advantage of a new fourth-order direct solver for the Poisson equation to ensure the incompressibility constraint down to machine zero. For introducing a deformable body in fluid flow, the volume penalization method is used. A Lagrangian structured grid with prescribed motion covers the deformable body interacting with the surrounding fluid due to the hydrodynamic forces and moment calculated on the Eulerian reference grid. An efficient law for curvature control of an anguilliform fish, swimming to a prescribed goal, is proposed. Validation of the developed method shows the efficiency and expected accuracy of the algorithm for fish-like swimming and also for a variety of fluid/solid interaction problems.
Seyed Amin Ghaffari, Stéphane Viazzo, Kai Schneider, Patrick Bontoux. Simulation of forced deformable bodies interacting with two-dimensional incompressible flows: Application to fish-like swimming. International Journal of Heat and Fluid Flow, 2015, Theme special issue celebrating the 75th birthdays of Brian Launder and Kemo Hanjalic, 51, pp.88-109. ⟨10.1016/j.ijheatfluidflow.2014.10.023⟩. ⟨hal-00967077v2⟩
Journal: International Journal of Heat and Fluid Flow
Seyed Amin Ghaffari, Stéphane Viazzo, Kai Schneider, Patrick Bontoux. Simulation of forced deformable bodies interacting with two-dimensional incompressible flows: Application to fish-like swimming. International Journal of Heat and Fluid Flow, 2015, Theme special issue celebrating the 75th birthdays of Brian Launder and Kemo Hanjalic, 51, pp.88-109. ⟨10.1016/j.ijheatfluidflow.2014.10.023⟩. ⟨hal-00967077v2⟩ Plus de détails...
We present an efficient algorithm for simulation of deformable bodies interacting with two-dimensional incompressible flows. The temporal and spatial discretizations of the Navier-Stokes equations in vorticity stream-function formulation are based on classical fourth-order Runge-Kutta and compact finite differences, respectively. Using a uniform Cartesian grid we benefit from the advantage of a new fourth-order direct solver for the Poisson equation to ensure the incompressibility constraint down to machine zero. For introducing a deformable body in fluid flow, the volume penalization method is used. A Lagrangian structured grid with prescribed motion covers the deformable body interacting with the surrounding fluid due to the hydrodynamic forces and moment calculated on the Eulerian reference grid. An efficient law for curvature control of an anguilliform fish, swimming to a prescribed goal, is proposed. Validation of the developed method shows the efficiency and expected accuracy of the algorithm for fish-like swimming and also for a variety of fluid/solid interaction problems.
Seyed Amin Ghaffari, Stéphane Viazzo, Kai Schneider, Patrick Bontoux. Simulation of forced deformable bodies interacting with two-dimensional incompressible flows: Application to fish-like swimming. International Journal of Heat and Fluid Flow, 2015, Theme special issue celebrating the 75th birthdays of Brian Launder and Kemo Hanjalic, 51, pp.88-109. ⟨10.1016/j.ijheatfluidflow.2014.10.023⟩. ⟨hal-00967077v2⟩
Journal: International Journal of Heat and Fluid Flow
Bouchra Bensiali, Guillaume Chiavassa, Jacques Liandrat. Penalization of Robin boundary conditions. Applied Numerical Mathematics: an IMACS journal, 2015, 96, pp.134-152. ⟨hal-01266091⟩ Plus de détails...
This paper is devoted to the mathematical analysis of a method based on fictitious domain approach. Boundary conditions of Robin type (also known as Fourier boundary conditions) are enforced using a penalization method. A complete description of the method and a full analysis are provided for univariate elliptic and parabolic problems using finite difference approximation. Numerical evidence of the predicted estimations is provided as well as numerical results for a nonlinear problem and a first extension of the method in the bivariate situation is proposed.
Bouchra Bensiali, Guillaume Chiavassa, Jacques Liandrat. Penalization of Robin boundary conditions. Applied Numerical Mathematics: an IMACS journal, 2015, 96, pp.134-152. ⟨hal-01266091⟩
Journal: Applied Numerical Mathematics: an IMACS journal
Aymeric Lamorlette, Mohamad El Houssami, Jan C. Thomas, Albert Simeoni, Dominique Morvan. A dimensional analysis of forest fuel layer ignition model: Application to the ignition of pine needle litters. Journal of Fire Sciences, 2015, pp.NC. ⟨10.1177/ToBeAssigned⟩. ⟨hal-01157866⟩ Plus de détails...
This paper deals with the physical modelling of forest fuel layer ignition. A model based on momentum, fluid and solid phase energy equations is written for a fuel layer and a dimensional analysis is performed. This analysis allows to enlighten two relevant dimensionless groups regarding the dimensionless time to ignition of a fuel layer and also provides a suited scaling for the fluid velocity inside the fuel layer during ignition. A correlation for the time to ignition is then fitted on experimental data obtained using a FM-Global Fire Propagation Apparatus (FPA) for different pine species with a closed basket. A good agreement is found, emphasizing the relevance of the dimensionless groups and the thermally thick behaviour of the solid particles during the ignition process under incident radiant heat flux as low as 8 − 12kW.m −2 .
Aymeric Lamorlette, Mohamad El Houssami, Jan C. Thomas, Albert Simeoni, Dominique Morvan. A dimensional analysis of forest fuel layer ignition model: Application to the ignition of pine needle litters. Journal of Fire Sciences, 2015, pp.NC. ⟨10.1177/ToBeAssigned⟩. ⟨hal-01157866⟩
Aymeric Lamorlette, Fabien Candelier. Thermal behavior of solid particles at ignition: Theoretical limit between thermally thick and thin solids. International Journal of Heat and Mass Transfer, 2015, pp.117-122. ⟨10.1016/j.ijheatmasstransfer.2014.11.037⟩. ⟨hal-01096409⟩ Plus de détails...
This paper deals with thermal behaviors of solid particles at ignition in attempting to theoretically delineate transition between thermally thick and thin behavior when a solid target is exposed to a radiant heat flux. In order to evaluate classical asymptotic relation accuracy and limiting range, models are developed for finite-depth target in both Cartesian and cylindrical coordinates, allowing to enhance asymptotic relations. Comparison between finite-depth target solutions and asymptotic solutions finally provides a mapping which allows the suited relation for ignition time calculation to be determined, regarding ignition conditions. This mapping then suggests some interesting consequences on forest fuel ignition and fire propagation modeling, since asymptotic models seem to overlap on large regions.
Aymeric Lamorlette, Fabien Candelier. Thermal behavior of solid particles at ignition: Theoretical limit between thermally thick and thin solids. International Journal of Heat and Mass Transfer, 2015, pp.117-122. ⟨10.1016/j.ijheatmasstransfer.2014.11.037⟩. ⟨hal-01096409⟩
Journal: International Journal of Heat and Mass Transfer
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michel Lebars. Velocity and temperature measurements in a turbulent water-filled Taylor-Couette-Poiseuille system. International Journal of Thermal Sciences, 2015. ⟨hal-01467719⟩ Plus de détails...
Motivated by the difficulties encountered by engineers to cool down the rotating shafts of industrial machines, the present work investigates the heat and mass transfers in the rotor-stator gap of a Taylor–Couette system with an axial water flow characterized by an aspect ratio Γ = 50 and a radius ratio η = 8/9. Extensive velocity and temperature measurements have been performed on an experimental set-up for a wide range of the flow parameters: the axial Reynolds number Re and the Taylor number Ta reach the values 1.12 × 104 and 7.9 × 107 respectively. In particular, coherent structures close to the rotating wall were measured by Stereo Particle Image Velocimetry. A correlation for the Nusselt number Nu on the rotating wall is finally provided against the axial Reynolds, Taylor and Prandtl numbers. Nu is proportional to the Taylor number to the power ∼0.13 close to the exponent 1/7 highlighted by an analytical model. This small exponent traduces the control of heat transfers by the rotating viscous layer and thus may explain the difficulty met by engineers to develop strategies for the effective cooling of such rotating apparatus.
Adrien Aubert, Sébastien Poncet, Patrice Le Gal, Stéphane Viazzo, Michel Lebars. Velocity and temperature measurements in a turbulent water-filled Taylor-Couette-Poiseuille system. International Journal of Thermal Sciences, 2015. ⟨hal-01467719⟩
Journal: International Journal of Thermal Sciences
Dominique Morvan. Numerical study of the behaviour of a surface fire propagating through a firebreak built in a Mediterranean shrub layer. Fire Safety Journal, 2015, 71 (7), pp.34-48. ⟨10.1016/j.firesaf.2014.11.012⟩. ⟨hal-01297711⟩ Plus de détails...
The efficiency of a firebreak, built in a shrubland has been studied numerically using a multiphase physical model. The physical mechanisms governing the propagation of the surface fire and the consequences upon the temperature signal and the radiative heat flux received by a target located at 1 m above the ground level, have been firstly studied before positioning the firebreak. The role played by the flame and the recirculation of hot gases to the ignition of unburned fuel (especially the dry grass) ahead of the fire front have been clearly identified. Four values of the firebreak width LC (ranged between 5 and 20 m) and 3 values of wind velocities (ranged between 1 and 8 m/s) have been tested. The simulations show that above a threshold value of this parameter, even if a small amount of the fuel located on the opposite side of the firebreak was ignited, the released energy was not sufficient to sustain the propagation of the surface fire after crossing the firebreak.
Dominique Morvan. Numerical study of the behaviour of a surface fire propagating through a firebreak built in a Mediterranean shrub layer. Fire Safety Journal, 2015, 71 (7), pp.34-48. ⟨10.1016/j.firesaf.2014.11.012⟩. ⟨hal-01297711⟩
Richard Saurel, Sebastien Le Martelot, Robert Tosello, Emmanuel Lapebie. Symmetric model of compressible granular mixtures with permeable interfaces. Physics of Fluids, 2014, 26 (12), ⟨10.1063/1.4903259⟩. ⟨hal-01459320⟩ Plus de détails...
Compressible granular materials are involved in many applications, some of them being related to energetic porous media. Gas permeation effects are important during their compaction stage, as well as their eventual chemical decomposition. Also, many situations involve porous media separated from pure fluids through two-phase interfaces. It is thus important to develop theoretical and numerical formulations to deal with granular materials in the presence of both two-phase interfaces and gas permeation effects. Similar topic was addressed for fluid mixtures and interfaces with the Discrete Equations Method (DEM) [R. Abgrall and R. Saurel, ``Discrete equations for physical and numerical compressible multiphase mixtures,''J. Comput. Phys. 186 (2), 361-396 (2003)] but it seemed impossible to extend this approach to granular media as intergranular stress [K. K. Kuo, V. Yang, and B. B. Moore, ``Intragranular stress, particle-wall friction and speed of sound in granular propellant beds,'' J. Ballist. 4 (1), 697-730 (1980)] and associated configuration energy [J. B. Bdzil, R. Menikoff, S. F. Son, A. K. Kapila, and D. S. Stewart, `` Two-phase modeling of deflagration-to-detonation transition in granular materials: A critical examination of modeling issues,'' Phys. Fluids 11, 378 (1999)] were present with significant effects. An approach to deal with fluid-porous media interfaces was derived in Saurel et al. [''Modelling dynamic and irreversible powder compaction,'' J. Fluid Mech. 664, 348-396 (2010)] but its validity was restricted to weak velocity disequilibrium only. Thanks to a deeper analysis, the DEM is successfully extended to granular media modelling in the present paper. It results in an enhanced version of the Baer and Nunziato [''A two-phase mixture theory for the deflagration-to-detonation transition (DDT) in reactive granular materials,'' Int. J. Multiphase Flow 12 (6), 861-889 (1986)] model as symmetry of the formulation is now preserved. Several computational examples are shown to validate and illustrate method's capabilities. (C) 2014 AIP Publishing LLC.
Richard Saurel, Sebastien Le Martelot, Robert Tosello, Emmanuel Lapebie. Symmetric model of compressible granular mixtures with permeable interfaces. Physics of Fluids, 2014, 26 (12), ⟨10.1063/1.4903259⟩. ⟨hal-01459320⟩
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse
. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩ Plus de détails...
Le procédé d’osmose inverse s’impose aujourd'hui dans la production d’eau douce par dessalement. Des avancées en matière de prédiction des performances de ce procédé s’avèrent précieuses dans l’optimisation rapide et peu coûteuse des conditions de fonctionnement. L’interaction entre les propriétés de la membrane et les phénomènes prépondérants (polarisation de concentration, pression osmotique...) constitue un problème scientifiquement complexe, traité dans cette étude via une approche modélisation numérique-simulation-expérimentation, une question centrale pour le génie des procédés.
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse
. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩ Plus de détails...
Le procédé d’osmose inverse s’impose aujourd'hui dans la production d’eau douce par dessalement. Des avancées en matière de prédiction des performances de ce procédé s’avèrent précieuses dans l’optimisation rapide et peu coûteuse des conditions de fonctionnement. L’interaction entre les propriétés de la membrane et les phénomènes prépondérants (polarisation de concentration, pression osmotique...) constitue un problème scientifiquement complexe, traité dans cette étude via une approche modélisation numérique-simulation-expérimentation, une question centrale pour le génie des procédés.
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩
Sébastien Poncet, Stéphane Viazzo, Oguic Romain. Large eddy simulations of Taylor-Couette-Poiseuille flows in a narrow-gap system. Physics of Fluids, 2014, 26 (10), pp.105108. ⟨10.1063/1.4899196⟩. ⟨hal-01083052⟩ Plus de détails...
The present paper concerns Large-Eddy Simulations (LES) of turbulent Taylor-Couette-Poiseuille flows in a narrow-gap cavity for six different combinations of rotational and axial Reynolds numbers. The in-house numerical code has been first validated in a middle-gap cavity. Two sets of refined LES results, using the Wall-Adapting Local EddyViscosity(WALE) and theDynamic Smagorinsky subgrid-scale models availablewithin an in-house code based on high-order compact schemes, have been then compared with no noticeable difference on the mean flow field and theturbulent statistics. The WALE model enabling a saving of about 12% of computational effort has been finally used to investigate the influence on the hydrodynamics of the swirl parameter N within the range [1.49 − 6.71]. The swirl parameter N, which compares the effects of rotation of the inner cylinder and the axial flowrate, does not influence significantly the mean velocity profiles. Turbulence intensities are enhanced with increasing values of N with remarkably high peak values within the boundary layers. The inner rotating cylinder has a destabilizing effect inducing asymmetric profiles of the Reynolds stress tensor components. The rotor and stator boundary layers exhibit the main characteristics of two-dimensional boundary layers.Turbulence is also mainly at two-component there. Thin coherent structures appearing as negative (resp. positive) spiral rolls are observed along the rotor (resp. stator) side. Their inclination angle depends strongly on the value of the swirl parameter, which fixes the intensity of the crossflow. On the other hand, the intensity and the size of the coherent structures observed within the boundary layers are governed by the effective Reynolds number. For its highest value, they penetrate the whole gap. Finally, the results have been extended to the non-isothermal case in the forced convection regime. A correlation for the Nusselt number along the rotor has been provided showing a much larger dependence on the axial Reynolds number thanexpected from previous published works, while it depends classically on the Taylor number to the power 0.145 and on the Prandtl number to the power 0.3.
Sébastien Poncet, Stéphane Viazzo, Oguic Romain. Large eddy simulations of Taylor-Couette-Poiseuille flows in a narrow-gap system. Physics of Fluids, 2014, 26 (10), pp.105108. ⟨10.1063/1.4899196⟩. ⟨hal-01083052⟩
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Wave simulation in 2D heterogeneous transversely isotropic porous media ă with fractional attenuation: A Cartesian grid approach. Journal of Computational Physics, 2014, 275, pp.118-142. ⟨10.1016/j.jcp.2014.07.002⟩. ⟨hal-01464704⟩ Plus de détails...
A time-domain numerical modeling of transversely isotropic Biot ă poroelastic waves is proposed in two dimensions. The viscous dissipation ă occurring in the pores is described using the dynamic permeability model ă developed by Johnson-Koplik-Dashen (JKD). Some of the coefficients in ă the Biot-JKD model are proportional to the square root of the frequency. ă In the time-domain, these coefficients introduce shifted fractional ă derivatives of order 1/2, involving a convolution product. Based on a ă diffusive representation, the convolution kernel is replaced by a finite ă number of memory variables that satisfy local-in-time ordinary ă differential equations, resulting in the Biot-DA (diffusive ă approximation) model. The properties of both the Biot-JKD and the ă Biot-DA models are analyzed: hyperbolicity, decrease of energy, ă dispersion. To determine the coefficients of the diffusive ă approximation, two approaches are analyzed: Gaussian quadratures and ă optimization methods in the frequency range of interest. The nonlinear ă optimization is shown to be the better way of determination. A splitting ă strategy is then applied to approximate numerically the Biot-DA ă equations. The propagative part is discretized using a fourth-order ADER ă scheme on a Cartesian grid, whereas the diffusive part is solved ă exactly. An immersed interface method is implemented to take into ă account heterogeneous media on a Cartesian grid and to discretize the ă jump conditions at interfaces. Numerical experiments are presented. ă Comparisons with analytical solutions show the efficiency and the ă accuracy of the approach, and some numerical experiments are performed ă to investigate wave phenomena in complex media, such as multiple ă scattering across a set of random scatterers. (C) 2014 Elsevier Inc. All ă rights reserved.
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Wave simulation in 2D heterogeneous transversely isotropic porous media ă with fractional attenuation: A Cartesian grid approach. Journal of Computational Physics, 2014, 275, pp.118-142. ⟨10.1016/j.jcp.2014.07.002⟩. ⟨hal-01464704⟩
Stéphane Viazzo, Sébastien Poncet. Numerical simulation of the flow stability in a high aspect ratio Taylor–Couette system submitted to a radial temperature gradient. Computers and Fluids, 2014, 101, pp.15-26. ⟨10.1016/j.compfluid.2014.05.025⟩. ⟨hal-01083054⟩ Plus de détails...
From 28 high-order DNS computations, one investigates the formation of instabilities due to the strong competition between an azimuthal flow induced by rotation and an axial flow due to convection in a tall Taylor–Couette apparatus (gamma=80; eta=0.8) submitted to a radial temperature gradient. One explores the richness of the transition diagram that reports seven different flow patterns appearing either as spiral rolls, wavy vortices or a combination of both depending on the Taylor and Rayleigh numbers. The partial spiral regime observed experimentally by Guillerm (2010) is not recovered at very low Rayleigh numbers. The spatio-temporal properties of the different spirals close to the threshold of the primary instability are fairly predicted and a new insight on the flow and thermal structures of the instabilities is gained from this study. Finally, the distributions of the Nusselt number against the Taylor number are established for various Rayleigh numbers.
Stéphane Viazzo, Sébastien Poncet. Numerical simulation of the flow stability in a high aspect ratio Taylor–Couette system submitted to a radial temperature gradient. Computers and Fluids, 2014, 101, pp.15-26. ⟨10.1016/j.compfluid.2014.05.025⟩. ⟨hal-01083054⟩
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Lean flame dynamics through a 2D lattice of alkane droplets in air. Combustion Science and Technology, 2014, 186 (2), pp.103-119. ⟨hal-00935131⟩ Plus de détails...
Flame propagation along a 1-D array or through a 2D-lattice of fuel droplets has long been suggested to schematize spray-flames spreading in a two-phase premixture. The present numerical work considers the fresh aerosol as a system of individual alkane droplets initially located at the nodes of a face-centered 2D-lattice, surrounded by a variable mixture of alkane and air, in which the droplets can move. The main parameters of the study are s, the lattice path, and phi_ L , the liquid loading, which are both varied, whereas phi_T , the overall equivalence ratio, is maintained lean ( phi_T = 0.85). Main results are as follows: (a) For a large lattice path (or when the droplets are large enough), spreading occurs in two stages: a short time of combustion followed by a long time lag of vaporization and a classical triple flame (with a very short rich wing) spreads around the droplets; (b) spray-flame speed decreases as liquid loading increases; (c) an elementary model invoking both propagation stages allows us to interpret flame speed as a function of the sole parameter s × phi_ L ; (d) when the lattice path shortens, the spray-flame exhibits a pattern that continuously goes from this situation to the plane flame front.
Colette Nicoli, Bruno Denet, Pierre Haldenwang. Lean flame dynamics through a 2D lattice of alkane droplets in air. Combustion Science and Technology, 2014, 186 (2), pp.103-119. ⟨hal-00935131⟩
Joan Escandell, Isabelle Raspo, Evelyne Neau. Prediction of Solid Polycyclic Aromatic Hydrocarbons Solubility in Water with the NRTL-PR Model. Fluid Phase Equilibria, 2014, 362 (25), pp.87-95. ⟨10.1016/j.fluid.2013.09.009⟩. ⟨hal-00872639⟩ Plus de détails...
The accurate prediction of high pressure phase equilibria is crucial for the development and the design of chemical engineering processes. Among them the modeling of complex systems, such as petroleum fluids with water, has become more and more important with the exploitation of reservoirs in extreme conditions. The aim of this work is to explore the capability of the NRTL-PR model to predict the solubility of solid polycyclic aromatic hydrocarbons in water. For this purpose, we first validate our methodology for fluid phase equilibria predictions of aromatic hydrocarbons and gas (CO2, C2H6) mixtures. Finally, we consider the prediction of the solid solubility of PAH in water, by fitting group parameters either only on SLE data or on both LLE and SLE data of aromatic hydrocarbon-water binary systems.
Joan Escandell, Isabelle Raspo, Evelyne Neau. Prediction of Solid Polycyclic Aromatic Hydrocarbons Solubility in Water with the NRTL-PR Model. Fluid Phase Equilibria, 2014, 362 (25), pp.87-95. ⟨10.1016/j.fluid.2013.09.009⟩. ⟨hal-00872639⟩
Anthony Randriamampianina, Emilia Crespo del Arco. High resolution method for direct numerical simulation of the instability and transition in a baroclinic cavity. Thomas von Larcher, Paul D. Williams. Modelling atmospheric and oceanic flows: insights from laboratory experiments and numerical simulations, Wiley, chapter V.2, 2014, American Geophysical Union Series, 978-1-118-85593-5. ⟨hal-00993357⟩ Plus de détails...
Anthony Randriamampianina, Emilia Crespo del Arco. High resolution method for direct numerical simulation of the instability and transition in a baroclinic cavity. Thomas von Larcher, Paul D. Williams. Modelling atmospheric and oceanic flows: insights from laboratory experiments and numerical simulations, Wiley, chapter V.2, 2014, American Geophysical Union Series, 978-1-118-85593-5. ⟨hal-00993357⟩
Aymeric Lamorlette. Analytical modeling of solid material ignition under a radiant heat flux coming from a spreading fire front. Journal of Thermal Science and Engineering Applications, 2014, 6 (4), pp.044501. ⟨10.1115/1.4028204⟩. ⟨hal-01059491⟩ Plus de détails...
This study aims at characterizing ignition of solid targets exposed to spreading fire fronts. In order to model radiant heat fluxes on targets in a realistic way, polynomial heat fluxes are chosen. Analytical solutions for the solid surface temperature evolution regarding different time-varying heat fluxes are discussed for high thermal inertia solids using a mathematical formalism, which allows for the methodology to be extended to the case of low thermal inertia. This formulation also allows calculation of ignition times for more realistic time-dependent fluxes than previous studies on the topic, providing a more general solution to the problem of solid material ignition. Polynomial coefficients are then obtained fitting heat flux coming from absorbing-emitting flames. A characterization of solid material ignition times regarding fire front rate of spread (ROS) is finally performed, showing the need to accurately model heat flux variations in ignition time calculations.
Aymeric Lamorlette. Analytical modeling of solid material ignition under a radiant heat flux coming from a spreading fire front. Journal of Thermal Science and Engineering Applications, 2014, 6 (4), pp.044501. ⟨10.1115/1.4028204⟩. ⟨hal-01059491⟩
Journal: Journal of Thermal Science and Engineering Applications
Anthony Randriamampianina, Emilia Crespo del Arco. High resolution method for direct numerical simulation of the instability and transition in a baroclinic cavity. Thomas von Larcher, Paul D. Williams. Modelling atmospheric and oceanic flows: insights from laboratory experiments and numerical simulations, Wiley, chapter V.2, 2014, American Geophysical Union Series, 978-1-118-85593-5. ⟨hal-00993357⟩ Plus de détails...
Anthony Randriamampianina, Emilia Crespo del Arco. High resolution method for direct numerical simulation of the instability and transition in a baroclinic cavity. Thomas von Larcher, Paul D. Williams. Modelling atmospheric and oceanic flows: insights from laboratory experiments and numerical simulations, Wiley, chapter V.2, 2014, American Geophysical Union Series, 978-1-118-85593-5. ⟨hal-00993357⟩
Dominique Morvan. Wind effects, unsteady behaviors, and regimes of propagation of surface fires in open field. Combustion Science and Technology, 2014, 186 (7), pp.869-888. ⟨10.1080/00102202.2014.885961⟩. ⟨hal-01049769⟩ Plus de détails...
The subject of this article concerns the unsteady effects (fire intensity, wind) upon the propagation and, more generally, the behavior of surface fires in open fields. The study focused on two sources of unsteadiness: the first one resulting from the regime of propagation (wind driven or plume dominated), which can affect greatly the behavior of the flame front and consequently the fire intensity, the second one resulting from the wind gusts associated with the conditions of flow of wind in real conditions. The study was based on numerical simulations, using a multiphase formulation, and on spectral analysis of the time evolution of the fire line intensity. The calculations were performed in 2D for a homogeneous vegetation layer (grassland) and for a large interval of wind conditions (10 m open wind velocity U10 ranged between 1 m/s and 25 m/s). The results have highlighted the link between the unsteady character of flame front behavior and the regime of propagation (plume dominated, wind driven). A particular interest was focused on the role played by two potential sources of instabilities, namely the Kelvin-Helmholtz instability (wind effects) and the thermo-convective instability (plume effects), upon the behavior of fires. A second set of simulations has been carried out using unsteady wind conditions, reproduced using sinusoidal boundary conditions for the streamwise velocity, with a frequency ranging between 0.5 Hz and 3 Hz.
Dominique Morvan. Wind effects, unsteady behaviors, and regimes of propagation of surface fires in open field. Combustion Science and Technology, 2014, 186 (7), pp.869-888. ⟨10.1080/00102202.2014.885961⟩. ⟨hal-01049769⟩
Aymeric Lamorlette. Quantification of ignition time uncertainty based on the classical ignition theory and Fourier analysis. Comptes Rendus Mécanique, 2014, 342 (8), pp.459 - 465. ⟨10.1016/j.crme.2014.06.002⟩. ⟨hal-01096403⟩ Plus de détails...
This study aims at modeling the effect of incoming heat flux fluctuations, on solid material ignition. In order to propose a general methodology based on the classical ignition theory that can be applied to any kind of solid target, kernels accounting for the target temperature response regarding an incoming heat flux are considered for thermally thick and thin solids with low or high thermal inertia. A Fourier decomposition of the incoming heat flux is then used to calculate the target response to harmonic heat fluxes. Finally, effects of harmonic fluctuations on ignition are discussed based on the previous analytical results, allowing to discriminate situations where ignition time is expected to be rather predictable from situations where ignition time is expected to be less predictable thanks to an uncertainty quantification of the ignition time. To cite this article: Aymeric Lamorlette, C. R. Mecanique 333 (2005).
Aymeric Lamorlette. Quantification of ignition time uncertainty based on the classical ignition theory and Fourier analysis. Comptes Rendus Mécanique, 2014, 342 (8), pp.459 - 465. ⟨10.1016/j.crme.2014.06.002⟩. ⟨hal-01096403⟩
B. Bernales, Pierre Haldenwang. Laminar flow analysis in a pipe with locally pressure-dependent leakage through the wall. European Journal of Mechanics - B/Fluids, 2014, 43, pp.100-109. ⟨10.1016/j.euromechflu.2013.07.006⟩. ⟨hal-01053307⟩ Plus de détails...
The paper analyzes the problem of the leaky pipe (or a porous-walled pipe), namely the laminar flow of a pure fluid that takes place in a pipe, the wall of which is composed of a porous material. This configuration is inspired by some watering systems or by the cross-flow (or tangential) filtration configuration for membrane separation or capillary flow. It assumes that the leakage through the wall (or permeate) results from the pressure difference between both sides of the pipe wall, and is here modeled by the Starling-Darcy law. The inner pressure along the pipe behaves accordingly with two competitive features: the viscous pressure drop competing against the pressure increase due to pipe axial flow deceleration. It is long known that both features compensate at a critical value, R-t(iso), of the transverse Reynolds number R-t (based on transpiration velocity); this corresponds to the only situation where the pressure remains uniform along the channel. The case with uniform leakage known as Berman flow possesses a similarity solution due to Yuan and Finkelstein (1956) [2] for the pipe configuration. The paper is aimed at extending the latter study to a non-uniform leakage depending linearly on local pressure. First, the similarity solution is revisited. Its expansion in a series of R-t allows us to propose a hierarchy of new ordinary differential equations (ODEs), that extend to small or moderate R-t the linear ODE proposed for the limit case R-t = 0 by Regirer (1960) [25]. As by-products, we propose approximate analytical solutions that solve the problem of the leaking pipe with increasing accuracy in the weakly non-linear case (WNL) (i.e. for small and moderate R-t). Finally, the validity of ODEs and WNL solutions is numerically checked with respect to flow simulations in the Prandtl approximation. (C) 2013 Elsevier Masson SAS. All rights reserved.
B. Bernales, Pierre Haldenwang. Laminar flow analysis in a pipe with locally pressure-dependent leakage through the wall. European Journal of Mechanics - B/Fluids, 2014, 43, pp.100-109. ⟨10.1016/j.euromechflu.2013.07.006⟩. ⟨hal-01053307⟩
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Wave simulation in 2D heterogeneous transversely isotropic porous media with fractional attenuation: a Cartesian grid approach. Journal of Computational Physics, 2014, 275, pp.118-142. ⟨hal-00949686v2⟩ Plus de détails...
A time-domain numerical modeling of transversely isotropic Biot poroelastic waves is proposed in two dimensions. The viscous dissipation occurring in the pores is described using the dynamic permeability model developed by Johnson-Koplik-Dashen (JKD). Some of the coefficients in the Biot-JKD model are proportional to the square root of the frequency. In the time-domain, these coefficients introduce shifted fractional derivatives of order 1/21/2, involving a convolution product. Based on a diffusive representation, the convolution kernel is replaced by a finite number of memory variables that satisfy local-in-time ordinary differential equations, resulting in the Biot-DA (diffusive approximation) model. The properties of both the Biot-JKD and the Biot-DA model are analyzed: hyperbolicity, decrease of energy, dispersion. To determine the coefficients of the diffusive approximation, two approaches are analyzed: Gaussian quadratures and optimization methods in the frequency range of interest. The nonlinear optimization is shown to be the better way of determination. A splitting strategy is then applied to approximate numerically the Biot-DA equations. The propagative part is discretized using a fourth-order ADER scheme on a Cartesian grid, whereas the diffusive part is solved exactly. An immersed interface method is implemented to take into account heterogeneous media on a Cartesian grid and to discretize the jump conditions at interfaces. Numerical experiments are presented. Comparisons with analytical solutions show the efficiency and the accuracy of the approach, and some numerical experiments are performed to investigate wave phenomena in complex media, such as multiple scattering across a set of random scatterers.
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Wave simulation in 2D heterogeneous transversely isotropic porous media with fractional attenuation: a Cartesian grid approach. Journal of Computational Physics, 2014, 275, pp.118-142. ⟨hal-00949686v2⟩
Dominique Morvan. Wind effects, unsteady behaviors, and regimes of propagation of surface fires in open field. Combustion Science and Technology, 2014, 186 (7), pp.869-888. ⟨10.1080/00102202.2014.885961⟩. ⟨hal-01049769⟩ Plus de détails...
The subject of this article concerns the unsteady effects (fire intensity, wind) upon the propagation and, more generally, the behavior of surface fires in open fields. The study focused on two sources of unsteadiness: the first one resulting from the regime of propagation (wind driven or plume dominated), which can affect greatly the behavior of the flame front and consequently the fire intensity, the second one resulting from the wind gusts associated with the conditions of flow of wind in real conditions. The study was based on numerical simulations, using a multiphase formulation, and on spectral analysis of the time evolution of the fire line intensity. The calculations were performed in 2D for a homogeneous vegetation layer (grassland) and for a large interval of wind conditions (10 m open wind velocity U10 ranged between 1 m/s and 25 m/s). The results have highlighted the link between the unsteady character of flame front behavior and the regime of propagation (plume dominated, wind driven). A particular interest was focused on the role played by two potential sources of instabilities, namely the Kelvin-Helmholtz instability (wind effects) and the thermo-convective instability (plume effects), upon the behavior of fires. A second set of simulations has been carried out using unsteady wind conditions, reproduced using sinusoidal boundary conditions for the streamwise velocity, with a frequency ranging between 0.5 Hz and 3 Hz.
Dominique Morvan. Wind effects, unsteady behaviors, and regimes of propagation of surface fires in open field. Combustion Science and Technology, 2014, 186 (7), pp.869-888. ⟨10.1080/00102202.2014.885961⟩. ⟨hal-01049769⟩
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. A time-domain numerical modeling of two-dimensional wave propagation in ă porous media with frequency-dependent dynamic permeability. Journal of the Acoustical Society of America, Acoustical Society of America, 2013, 134 (6, 2, SI), pp.4610-4623. ⟨10.1121/1.4824832⟩. ⟨hal-01464730⟩ Plus de détails...
An explicit finite-difference scheme is presented for solving the ă two-dimensional Biot equations of poroelasticity across the full range ă of frequencies. The key difficulty is to discretize the ă Johnson-Koplik-Dashen (JKD) model which describes the viscous ă dissipations in the pores. Indeed, the time-domain version of Biot-JKD ă model involves order 1/2 fractional derivatives which amount to a time ă convolution product. To avoid storing the past values of the solution, a ă diffusive representation of fractional derivatives is used: The ă convolution kernel is replaced by a finite number of memory variables ă that satisfy local-in-time ordinary differential equations. The ă coefficients of the diffusive representation follow from an optimization ă procedure of the dispersion relation. Then, various methods of ă scientific computing are applied: The propagative part of the equations ă is discretized using a fourth-order finite-difference scheme, whereas ă the diffusive part is solved exactly. An immersed interface method is ă implemented to discretize the geometry on a Cartesian grid, and also to ă discretize the jump conditions at interfaces. Numerical experiments are ă proposed in various realistic configurations. (C) 2013 Acoustical ă Society of America.
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. A time-domain numerical modeling of two-dimensional wave propagation in ă porous media with frequency-dependent dynamic permeability. Journal of the Acoustical Society of America, Acoustical Society of America, 2013, 134 (6, 2, SI), pp.4610-4623. ⟨10.1121/1.4824832⟩. ⟨hal-01464730⟩
Journal: Journal of the Acoustical Society of America
Sébastien Poncet, Thien Duy Nguyen, Souad Harmand, Julien Pellé, Riccardo da Soghe, et al.. Turbulent impinging jet flow into an unshrouded rotor-stator system: Hydrodynamics and heat transfer. International Journal of Heat and Fluid Flow, 2013, 44, pp.719-734. ⟨10.1016/j.ijheatfluidflow.2013.10.001⟩. ⟨hal-00976669⟩ Plus de détails...
New calculations using an innovative Reynolds Stress Model are compared to velocity measurements performed by Particle Image Velocimetry technique and the predictions of a k-w SST model in the case of an impinging jet flow onto a rotating disk in a discoidal and unshrouded rotor-stator system. The cavity is characterized by a dimensionless spacing interval G=0.02 and a low aspect ratio for the jet e/D=0.25. Jet Reynolds numbers ranging from 17200 to 43000 and rotational Reynolds numbers between 33000 and 532000 are considered. Three flow regions have been identified: a jet-dominated flow area at low radii characterized by a zero tangential velocity, a mixed region at intermediate radii and rotation-dominated flow region outwards. For all parameters, turbulence, which tends to the isotropic limit in the core, is much intense in a region located after the impingement zone. A relative good agreement between the PIV measurements and the predictions of the RSM has been obtained in terms of the radial distributions of the core-swirl ratio and of the turbulence intensities. The k-wSST model overestimates these flow characteristics in the jet dominated area. For the thermal field, the heat transfers are enhanced in the jet dominated region and decreases towards the periphery of the cavity. The jet Reynolds number appears to have a preponderant effect compared to the rotational one on the heat transfer distribution. The two RANS modelings compare quite well with the heat transfer measurements for these ranges of parameters.
Sébastien Poncet, Thien Duy Nguyen, Souad Harmand, Julien Pellé, Riccardo da Soghe, et al.. Turbulent impinging jet flow into an unshrouded rotor-stator system: Hydrodynamics and heat transfer. International Journal of Heat and Fluid Flow, 2013, 44, pp.719-734. ⟨10.1016/j.ijheatfluidflow.2013.10.001⟩. ⟨hal-00976669⟩
Journal: International Journal of Heat and Fluid Flow
Sébastien Poncet, Stéphane Viazzo, Adrien Aubert, Riccardo da Soghe, Cosimo Bianchini. Turbulent Couette-Taylor flows with endwall effects: a numerical benchmark. International Journal of Heat and Fluid Flow, 2013, 44, pp.229-238. ⟨10.1016/j.ijheatfluidflow.2013.05.018⟩. ⟨hal-00975636⟩ Plus de détails...
The accurate prediction of fluid flow within rotating systems has a primary role for the reliability and performance of rotating machineries. The selection of a suitable model to account for the effects of turbulence on such complex flows remains an open issue in the literature. This paper reports a numerical benchmark of different approaches available within commercial CFD solvers together with results obtained by means of in-house developed or open-source available research codes exploiting a suitable Reynolds Stress Model (RSM) closure, Large Eddy Simulation (LES) and a direct numerical simulation (DNS). The predictions are compared to the experimental data of Burin et al. (2010) in an original enclosed Couette-Taylor apparatus with endcap rings. The results are discussed in details for both the mean and turbulent fields. A particular attention has been turned to the scaling of the turbulent angular momentum G with the Reynolds number Re. By DNS, G is found to be proportional to Rea, the exponent a = 1.9 being constant in our case for the whole range of Reynolds numbers. Most of the approaches predict quite well the good trends apart from the k-w SST model, which provides relatively poor agreement with the experiments even for the mean tangential velocity profile. Among the RANS models, even though no approach appears to be fully satisfactory, the RSM closure offers the best overall agreement.
Sébastien Poncet, Stéphane Viazzo, Adrien Aubert, Riccardo da Soghe, Cosimo Bianchini. Turbulent Couette-Taylor flows with endwall effects: a numerical benchmark. International Journal of Heat and Fluid Flow, 2013, 44, pp.229-238. ⟨10.1016/j.ijheatfluidflow.2013.05.018⟩. ⟨hal-00975636⟩
Journal: International Journal of Heat and Fluid Flow
Sébastien Poncet, Stéphane Viazzo, Adrien Aubert, Riccardo da Soghe, Cosimo Bianchini. Turbulent Couette-Taylor flows with endwall effects: a numerical benchmark. International Journal of Heat and Fluid Flow, 2013, 44, pp.229-238. ⟨10.1016/j.ijheatfluidflow.2013.05.018⟩. ⟨hal-00975636⟩ Plus de détails...
The accurate prediction of fluid flow within rotating systems has a primary role for the reliability and performance of rotating machineries. The selection of a suitable model to account for the effects of turbulence on such complex flows remains an open issue in the literature. This paper reports a numerical benchmark of different approaches available within commercial CFD solvers together with results obtained by means of in-house developed or open-source available research codes exploiting a suitable Reynolds Stress Model (RSM) closure, Large Eddy Simulation (LES) and a direct numerical simulation (DNS). The predictions are compared to the experimental data of Burin et al. (2010) in an original enclosed Couette-Taylor apparatus with endcap rings. The results are discussed in details for both the mean and turbulent fields. A particular attention has been turned to the scaling of the turbulent angular momentum G with the Reynolds number Re. By DNS, G is found to be proportional to Rea, the exponent a = 1.9 being constant in our case for the whole range of Reynolds numbers. Most of the approaches predict quite well the good trends apart from the k-w SST model, which provides relatively poor agreement with the experiments even for the mean tangential velocity profile. Among the RANS models, even though no approach appears to be fully satisfactory, the RSM closure offers the best overall agreement.
Sébastien Poncet, Stéphane Viazzo, Adrien Aubert, Riccardo da Soghe, Cosimo Bianchini. Turbulent Couette-Taylor flows with endwall effects: a numerical benchmark. International Journal of Heat and Fluid Flow, 2013, 44, pp.229-238. ⟨10.1016/j.ijheatfluidflow.2013.05.018⟩. ⟨hal-00975636⟩
Journal: International Journal of Heat and Fluid Flow
Philippe Ghendrih, Thomas Auphan, B. Bensiali, Marco Bilanceri, K. Bodi, et al.. Divertor imbalance and divertor density regimes for ballooned cross-field turbulence. Journal of Nuclear Materials, 2013, 438, pp.S368-S371. ⟨10.1016/j.jnucmat.2013.01.070⟩. ⟨hal-00920748⟩ Plus de détails...
The ballooned nature of cross-field transport is shown to govern the steady state divertor imbalance of the energy flux leading to a factor 10 between the low field side and high field energy flux. An even stronger ratio is found for the divertor temperatures. Conversely the particle flux is expected to be a factor 10 larger on the high field side than on the low field side. The transition to detachment, close to divertor thermal collapse, exhibits several constraints to maintain steady state solutions. These constraints, related in particular to a large drop of the divertor density upon detachment, are shown to strongly correlate the pressure and particle flux variation along the field line and consequently the various loss channels. This delicate balance between different mechanisms is a possible understanding of the difficulty reported in detached plasma operation and simulation.
Philippe Ghendrih, Thomas Auphan, B. Bensiali, Marco Bilanceri, K. Bodi, et al.. Divertor imbalance and divertor density regimes for ballooned cross-field turbulence. Journal of Nuclear Materials, 2013, 438, pp.S368-S371. ⟨10.1016/j.jnucmat.2013.01.070⟩. ⟨hal-00920748⟩
Djilali Ameur, Isabelle Raspo. Numerical Simulation of the Poiseuille-Rayleigh-Bénard Instability for a Supercritical Fluid in a Mini-channel. Computational Thermal Sciences, 2013, 5 (2), pp.107-118. ⟨10.1615/ComputThermalScien.2013006169⟩. ⟨hal-00834707⟩ Plus de détails...
The Poiseuille-Rayleigh-Bénard problem, involving the onset of thermoconvective structures in channels heated from below, was the subject of many theoretical, numerical and experimental studies for incompressible flows or perfect gas. However, to the authors' knowledge, this problem was never studied for supercritical fluids. The objective of this paper is to study the influence of the specific properties of such fluids on thermoconvective instability phenomena compared with those observed in the perfect gas case. The effect of the distance to the critical point is also investigated. The numerical approach used is based on the Navier-Stokes equations in the framework of the low Mach number approximation.
Djilali Ameur, Isabelle Raspo. Numerical Simulation of the Poiseuille-Rayleigh-Bénard Instability for a Supercritical Fluid in a Mini-channel. Computational Thermal Sciences, 2013, 5 (2), pp.107-118. ⟨10.1615/ComputThermalScien.2013006169⟩. ⟨hal-00834707⟩
Djilali Ameur, Isabelle Raspo. Numerical Simulation of the Poiseuille-Rayleigh-Bénard Instability for a Supercritical Fluid in a Mini-channel. Computational Thermal Sciences, 2013, 5 (2), pp.107-118. ⟨10.1615/ComputThermalScien.2013006169⟩. ⟨hal-00834707⟩ Plus de détails...
The Poiseuille-Rayleigh-Bénard problem, involving the onset of thermoconvective structures in channels heated from below, was the subject of many theoretical, numerical and experimental studies for incompressible flows or perfect gas. However, to the authors' knowledge, this problem was never studied for supercritical fluids. The objective of this paper is to study the influence of the specific properties of such fluids on thermoconvective instability phenomena compared with those observed in the perfect gas case. The effect of the distance to the critical point is also investigated. The numerical approach used is based on the Navier-Stokes equations in the framework of the low Mach number approximation.
Djilali Ameur, Isabelle Raspo. Numerical Simulation of the Poiseuille-Rayleigh-Bénard Instability for a Supercritical Fluid in a Mini-channel. Computational Thermal Sciences, 2013, 5 (2), pp.107-118. ⟨10.1615/ComputThermalScien.2013006169⟩. ⟨hal-00834707⟩
K. Gavrilov, Dominique Morvan, Gilbert Accary, Dimitry Lyubimov, Sofiane Meradji. Numerical simulation of coherent turbulent structures and of passive scalar dispersion in a canopy sub-layer. Computers and Fluids, 2013, LES of turbulence aeroacoustics and combustion, 78, pp.54-62. ⟨10.1016/j.compfluid.2012.08.021⟩. ⟨hal-01030794⟩ Plus de détails...
This study deals with the problem of turbulent atmospheric boundary-layer flow over a forest canopy. Numerous previous works showed that this flow presents more similarities with a mixing-layer flow than with the standard boundary-layer flow. In this paper, this problem was studied for homogeneous canopies, using large eddy simulation (LES). The numerical results reproduced correctly the various steps of development of this flow: the appearance of a first generation of coherent structures resulting from the development of a primary Kelvin-Helmholtz instability, the reorganization of these structures, by vortex pairing and kinking, the development of a secondary instability and the formation of horseshoe vortices. Then, the process of transport of a passive scalar from a forest canopy into a clear atmosphere was studied in two cases, i.e., when the passive scalar concentration at the surface foliage is either constant or time-varying. Even though this small difference has little influence on the concentration patterns, the results showed that it can significantly affect the concentration magnitude as well as the dynamics of the total concentration in the atmosphere.
K. Gavrilov, Dominique Morvan, Gilbert Accary, Dimitry Lyubimov, Sofiane Meradji. Numerical simulation of coherent turbulent structures and of passive scalar dispersion in a canopy sub-layer. Computers and Fluids, 2013, LES of turbulence aeroacoustics and combustion, 78, pp.54-62. ⟨10.1016/j.compfluid.2012.08.021⟩. ⟨hal-01030794⟩
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Biot-JKD model: simulation of 1D transient poroelastic waves with fractional derivatives. Journal of Computational Physics, 2013, 237, pp.1-20. ⟨10.1016/j.jcp.2012.12.003⟩. ⟨hal-00713127v2⟩ Plus de détails...
A time-domain numerical modeling of Biot poroelastic waves is presented. The viscous dissipation occurring in the pores is described using the dynamic permeability model developed by Johnson-Koplik-Dashen (JKD). Some of the coefficients in the Biot-JKD model are proportional to the square root of the frequency: in the time-domain, these coefficients introduce order 1/2 shifted fractional derivatives involving a convolution product. Based on a diffusive representation, the convolution kernel is replaced by a finite number of memory variables that satisfy local-in-time ordinary differential equations. Thanks to the dispersion relation, the coefficients in the diffusive representation are obtained by performing an optimization procedure in the frequency range of interest. A splitting strategy is then applied numerically: the propagative part of Biot-JKD equations is discretized using a fourth-order ADER scheme on a Cartesian grid, whereas the diffusive part is solved exactly. Comparisons with analytical solutions show the efficiency and the accuracy of this approach.
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. Biot-JKD model: simulation of 1D transient poroelastic waves with fractional derivatives. Journal of Computational Physics, 2013, 237, pp.1-20. ⟨10.1016/j.jcp.2012.12.003⟩. ⟨hal-00713127v2⟩
Anthony Randriamampianina. Inertia gravity waves characteristics within a baroclinic cavity. Comptes Rendus Mécanique, 2013, 341 (6), pp.547-552. ⟨10.1016/j.crme.2013.01.006⟩. ⟨hal-00946827⟩ Plus de détails...
High-resolution direct numerical simulations have shown the occurrence of inertia gravity waves simultaneously with baroclinic instabilities within a differentially heated rotating annulus, the "baroclinic cavity". The working fluid is characterised by a Prandtl number Pr = 16. A decomposition technique applied to the dependent variables has allowed us to separate in space and in time the contributions of the large-scale baroclinic structures from that of the small-scale fluctuations. These latter have been identified as inertia gravity waves from their dispersion relation. The present work is particularly focused on the mechanism responsible for the spontaneous generation of these waves.
Anthony Randriamampianina. Inertia gravity waves characteristics within a baroclinic cavity. Comptes Rendus Mécanique, 2013, 341 (6), pp.547-552. ⟨10.1016/j.crme.2013.01.006⟩. ⟨hal-00946827⟩
Dominique Morvan. Numerical study of the effect of fuel moisture content (FMC) upon the propagation of a surface fire on a flat terrain. Fire Safety Journal, 2013, 58, pp.121-131. ⟨10.1016/j.firesaf.2013.01.010⟩. ⟨hal-01030813⟩ Plus de détails...
This paper was devoted to clarify and evaluate how fuel moisture content (FMC) characterising a homogeneous vegetation layer (grass or shrubs), can affect the behaviour of surface fire. The approach used in this study was based on numerical simulations performed using a detailed fire physical model. The numerical results were analysed in terms of fire residence time, fire front depth, mass loss rate and rate of spread (ROS). Two windy conditions (calm and weak) were studied to evaluate the decay of the rate of spread (ROS) resulting from an increase of the fuel moisture content. The effect of wind velocity upon marginal burning conditions was also analysed. The numerical results were compared with empirical data of the literature.
Dominique Morvan. Numerical study of the effect of fuel moisture content (FMC) upon the propagation of a surface fire on a flat terrain. Fire Safety Journal, 2013, 58, pp.121-131. ⟨10.1016/j.firesaf.2013.01.010⟩. ⟨hal-01030813⟩
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. A time-domain numerical modeling of two-dimensional wave propagation in porous media with frequency-dependent dynamic permeability. Journal of the Acoustical Society of America, 2013, 134 (6), pp.4610-4623. ⟨10.1121/1.4824832⟩. ⟨hal-00736757⟩ Plus de détails...
An explicit finite-difference scheme is presented for solving the two-dimensional Biot equations of poroelasticity across the full range of frequencies. The key difficulty is to discretize the Johnson-Koplik-Dashen (JKD) model which describes the viscous dissipations in the pores. Indeed, the time-domain version of Biot-JKD model involves order 1/2 fractional derivatives which amounts to a time convolution product. To avoid storing the past values of the solution, a diffusive representation of fractional derivatives is used: the convolution kernel is replaced by a finite number of memory variables that satisfy local-in-time ordinary differential equations. The coefficients of the diffusive representation follow from an optimization procedure of the dispersion relation. Then, various methods of scientific computing are applied: the propagative part of the equations is discretized using a fourth-order finite-difference scheme, whereas the diffusive part is solved exactly. An immersed interface method is implemented to discretize the geometry on a Cartesian grid, and also to discretize the jump conditions at interfaces. Numerical experiments are proposed in various realistic configurations.
Emilie Blanc, Guillaume Chiavassa, Bruno Lombard. A time-domain numerical modeling of two-dimensional wave propagation in porous media with frequency-dependent dynamic permeability. Journal of the Acoustical Society of America, 2013, 134 (6), pp.4610-4623. ⟨10.1121/1.4824832⟩. ⟨hal-00736757⟩
Journal: Journal of the Acoustical Society of America
Dominique Morvan, Sofiane Meradji, William Mell. Interaction between head fire and backfire in grasslands. Fire Safety Journal, 2013, 58, pp.195-203. ⟨10.1016/j.firesaf.2013.01.027⟩. ⟨hal-01030810⟩ Plus de détails...
This paper deals with 3D numerical simulations of two fires fronts (head and backfire) propagating simultaneously through a grassland fuel. The simulations were carried out using a "fully" physical and three-dimensional fire model (namely WFDS). One of the objectives of this work, was to evaluate the potential for fully physical fire model to simulate the interactions between two fire fronts (a head fire and a backfire), in conditions similar to those encountered during suppression fire operations. A set of numerical simulations was first carried out for standalone head fires propagating through grasslands on a flat terrain and for various wind conditions ranging between 1 and 10 m/s. These results were compared with experimental data and numerical results from the literature. The same calculations were then repeated, with a backfire ignited at the downwind side of the plot. The numerical results highlighted that, for these particular conditions, head fire and backfire can interact, mainly, via two mechanisms: - at relatively large distances (greater than 10 m) the head fire acts on backfire as a screen and reduces the direct action of the wind flow on the backfire, - at relative small distances (nearly equal to 10 m) the gas flow (entrainment) generated in the vicinity of the head fire promotes the aspiration of the backfire towards the main fire front.
Dominique Morvan, Sofiane Meradji, William Mell. Interaction between head fire and backfire in grasslands. Fire Safety Journal, 2013, 58, pp.195-203. ⟨10.1016/j.firesaf.2013.01.027⟩. ⟨hal-01030810⟩
K. Gavrilov, Dominique Morvan, Gilbert Accary, Dimitry Lyubimov, Sofiane Meradji. Numerical simulation of coherent turbulent structures and of passive scalar dispersion in a canopy sub-layer. Computers and Fluids, Elsevier, 2013, 78, pp.54-62. ⟨10.1016/j.compfluid.2012.08.021⟩. ⟨hal-01030794⟩ Plus de détails...
This study deals with the problem of turbulent atmospheric boundary-layer flow over a forest canopy. Numerous previous works showed that this flow presents more similarities with a mixing-layer flow than with the standard boundary-layer flow. In this paper, this problem was studied for homogeneous canopies, using large eddy simulation (LES). The numerical results reproduced correctly the various steps of development of this flow: the appearance of a first generation of coherent structures resulting from the development of a primary Kelvin-Helmholtz instability, the reorganization of these structures, by vortex pairing and kinking, the development of a secondary instability and the formation of horseshoe vortices. Then, the process of transport of a passive scalar from a forest canopy into a clear atmosphere was studied in two cases, i.e., when the passive scalar concentration at the surface foliage is either constant or time-varying. Even though this small difference has little influence on the concentration patterns, the results showed that it can significantly affect the concentration magnitude as well as the dynamics of the total concentration in the atmosphere.
K. Gavrilov, Dominique Morvan, Gilbert Accary, Dimitry Lyubimov, Sofiane Meradji. Numerical simulation of coherent turbulent structures and of passive scalar dispersion in a canopy sub-layer. Computers and Fluids, Elsevier, 2013, 78, pp.54-62. ⟨10.1016/j.compfluid.2012.08.021⟩. ⟨hal-01030794⟩
Dominique Morvan, Sofiane Meradji, William Mell. Interaction between head fire and backfire in grasslands. Fire Safety Journal, Elsevier, 2013, 58, pp.195-203. ⟨10.1016/j.firesaf.2013.01.027⟩. ⟨hal-01030810⟩ Plus de détails...
This paper deals with 3D numerical simulations of two fires fronts (head and backfire) propagating simultaneously through a grassland fuel. The simulations were carried out using a "fully" physical and three-dimensional fire model (namely WFDS). One of the objectives of this work, was to evaluate the potential for fully physical fire model to simulate the interactions between two fire fronts (a head fire and a backfire), in conditions similar to those encountered during suppression fire operations. A set of numerical simulations was first carried out for standalone head fires propagating through grasslands on a flat terrain and for various wind conditions ranging between 1 and 10 m/s. These results were compared with experimental data and numerical results from the literature. The same calculations were then repeated, with a backfire ignited at the downwind side of the plot. The numerical results highlighted that, for these particular conditions, head fire and backfire can interact, mainly, via two mechanisms: - at relatively large distances (greater than 10 m) the head fire acts on backfire as a screen and reduces the direct action of the wind flow on the backfire, - at relative small distances (nearly equal to 10 m) the gas flow (entrainment) generated in the vicinity of the head fire promotes the aspiration of the backfire towards the main fire front.
Dominique Morvan, Sofiane Meradji, William Mell. Interaction between head fire and backfire in grasslands. Fire Safety Journal, Elsevier, 2013, 58, pp.195-203. ⟨10.1016/j.firesaf.2013.01.027⟩. ⟨hal-01030810⟩
Konstantin Gavrilov, Dmitri Lyubimov, Dominique Morvan, Gilbert Accary, Sofiane Meradji. Admixture transport model for atmospheric boundary layer flow over forest canopy. N. I. Lobachevsky Bulletin de l'Université de Ninji-Novgorod, 1 (3), pp.244-252, 2013, La Modélisation Mathématique: Contôle Optimal. ⟨hal-01313312⟩ Plus de détails...
Konstantin Gavrilov, Dmitri Lyubimov, Dominique Morvan, Gilbert Accary, Sofiane Meradji. Admixture transport model for atmospheric boundary layer flow over forest canopy. N. I. Lobachevsky Bulletin de l'Université de Ninji-Novgorod, 1 (3), pp.244-252, 2013, La Modélisation Mathématique: Contôle Optimal. ⟨hal-01313312⟩
Guillaume Chiavassa, Bruno Lombard. Wave propagation across acoustic / Biot's media: a finite-difference method. Communications in Computational Physics, 2013, 13 (4), pp.985-1012. ⟨10.4208/cicp.140911.050412a⟩. ⟨hal-00623627v2⟩ Plus de détails...
Numerical methods are developed to simulate the wave propagation in heterogeneous 2D fluid / poroelastic media. Wave propagation is described by the usual acoustics equations (in the fluid medium) and by the low-frequency Biot's equations (in the porous medium). Interface conditions are introduced to model various hydraulic contacts between the two media: open pores, sealed pores, and imperfect pores. Well-possedness of the initial-boundary value problem is proven. Cartesian grid numerical methods previously developed in porous heterogeneous media are adapted to the present context: a fourth-order ADER scheme with Strang splitting for time-marching; a space-time mesh-refinement to capture the slow compressional wave predicted by Biot's theory; and an immersed interface method to discretize the interface conditions and to introduce a subcell resolution. Numerical experiments and comparisons with exact solutions are proposed for the three types of interface conditions, demonstrating the accuracy of the approach.
Guillaume Chiavassa, Bruno Lombard. Wave propagation across acoustic / Biot's media: a finite-difference method. Communications in Computational Physics, 2013, 13 (4), pp.985-1012. ⟨10.4208/cicp.140911.050412a⟩. ⟨hal-00623627v2⟩
Héctor Barrios-Pina, Stéphane Viazzo, Claude Rey. A numerical study of laminar and transitional mixed convection flow over a backward-facing step. Computers and Fluids, 2012, 56 (1-2), pp.77-91. ⟨10.1016/j.compfluid.2011.11.016⟩. ⟨hal-01299345⟩ Plus de détails...
This work focuses on the study of the transition from steady to chaotic behavior in mixed convection flow over a backward-facing step. Direct numerical simulations are performed in a two-dimensional horizontal channel of expansion ratio ER = 2 at step level. The effects of the temperature difference between the heated bottom wall and the inflow temperature are investigated by keeping constant the Richardson number at 1. The covered range of Grashof and Reynolds numbers is respectively 3.31 × 104 ⩽ Gr ⩽ 2.72 × 105 and 182.03 ⩽ Re ⩽ 521.34. The thermal and dynamical instabilities which cause the onset of unsteady flow are described in detail. A spectral and phase portrait analysis of the temperature time series allows us to observe that the transition from steady to chaotic flow occurs by period-doubling bifurcations.
Héctor Barrios-Pina, Stéphane Viazzo, Claude Rey. A numerical study of laminar and transitional mixed convection flow over a backward-facing step. Computers and Fluids, 2012, 56 (1-2), pp.77-91. ⟨10.1016/j.compfluid.2011.11.016⟩. ⟨hal-01299345⟩
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩ Plus de détails...
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩
Aymeric Lamorlette, Anthony Collin. Analytical quantification of convective heat transfer inside vegetal structures. International Journal of Thermal Sciences, 2012, 57, pp.78-84. ⟨10.1016/j.ijthermalsci.2012.02.010⟩. ⟨hal-01297730⟩ Plus de détails...
Within the scope of environmental modelling, convective heat transfer between a vegetal structure and its surrounding medium remains to be adequately described. However, for some applications, such as forest fire modelling, convective heat transfer is one of the factors responsible for vertical fire transitions, from ground level to the tree crowns. These fires are the most dangerous because their rates of spread can reach high speeds, around 1 m per second. An accurate characterization of this transfer is therefore important for fire propagation modelling. This study presents an attempt to formulate an analytical modelling of the convective heat transfer coefficient inside vegetal structures generated using an Iterated Function Systems (IFS) which only depends on the IFS parameters (parameters helpful to generate vegetal structures). The results obtained using this formula are compared with previously computed numerical results to evaluate their accuracy. The maximal discrepancies were found to be around 6% which proves the efficiency of the present model.
Aymeric Lamorlette, Anthony Collin. Analytical quantification of convective heat transfer inside vegetal structures. International Journal of Thermal Sciences, 2012, 57, pp.78-84. ⟨10.1016/j.ijthermalsci.2012.02.010⟩. ⟨hal-01297730⟩
Journal: International Journal of Thermal Sciences
Wave propagation in a stratified fluid / porous medium is studied here using analytical and numerical methods. The semi-analytical method is based on an exact stiffness matrix method coupled with a matrix conditioning procedure, preventing the occurrence of poorly conditioned numerical systems. Special attention is paid to calculating the Fourier integrals. The numerical method is based on a high order finite-difference time-domain scheme. Mesh refinement is applied near the interfaces to discretize the slow compressional diffusive wave predicted by Biot's theory. Lastly, an immersed interface method is used to discretize the boundary conditions. The numerical benchmarks are based on realistic soil parameters and on various degrees of hydraulic contact at the fluid / porous boundary. The time evolution of the acoustic pressure and the porous velocity is plotted in the case of one and four interfaces. The excellent level of agreement found to exist between the two approaches confirms the validity of both methods, which cross-checks them and provides useful tools for future researches.
Gaëlle Lefeuve-Mesgouez, Arnaud Mesgouez, Guillaume Chiavassa, Bruno Lombard. Semi-analytical and numerical methods for computing transient waves in 2D acoustic / poroelastic stratified media. Wave Motion, 2012, 49-7 (7), pp.667-680. ⟨10.1016/j.wavemoti.2012.04.006⟩. ⟨hal-00667795v2⟩
Experiments were carried out on reversed weak laminar inclined fountains to asses that unstable modes of round fountains are disturbed by the inclination. Indeed, compared to fountains developing on horizontal wall, some modes disappeared while others are split in several modes. This paper aims at describing and mapping these new modes regarding to the inclination and the inlet velocity. Explanations about what made the unstable modes evolve are also proposed. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Joan Escandell, Evelyne Neau, Christophe Nicolas. A new formulation of the predictive NRTL-PR model in terms of kij mixing rules. Extension of the group contributions for the modeling of hydrocarbons in the presence of associating compounds. Fluid Phase Equilibria, 2011, 301 (1), pp.80-97. ⟨10.1016/j.fluid.2010.11.009⟩. ⟨hal-01464747⟩ Plus de détails...
A generalized NRTL model was previously proposed for the modeling of non ideal systems and was extended to the prediction of phase equilibria under pressure according to the cubic NRTL-PR EoS. In this work, the model is reformulated with a predictive kij temperature and composition dependent mixing rule and new interaction parameters are proposed between permanent gases, ethane and nitrogen with hydrocarbons, ethane with water and ethylene glycol. Results obtained for excess enthalpies, liquid–vapor and liquid–liquid equilibria are compared with those provided by the literature models, such as VTPR, PPR78, CPA and SRKm. A wide variety of mixtures formed by very asymmetric compounds, such as hydrocarbons, water and ethylene glycols are considered and special attention is paid to the evolution of kij with respect to mole fractions and temperature.
Joan Escandell, Evelyne Neau, Christophe Nicolas. A new formulation of the predictive NRTL-PR model in terms of kij mixing rules. Extension of the group contributions for the modeling of hydrocarbons in the presence of associating compounds. Fluid Phase Equilibria, 2011, 301 (1), pp.80-97. ⟨10.1016/j.fluid.2010.11.009⟩. ⟨hal-01464747⟩
Pierre Haldenwang, Pierrette Guichardon. Pressure runaway in a 2D plane channel with permeable walls submitted to pressure-dependent suction. European Journal of Mechanics - B/Fluids, 2011, 30 (2), pp.177-183. ⟨10.1016/j.euromechflu.2010.09.007⟩. ⟨hal-00905831⟩ Plus de détails...
A leaking duct carries a flow that is a characteristic of several applications. Devices for cross-flow microfiltration are composed of a duct, the walls of which are semi-permeable membranes. In subsurface irrigation, the walls of watering pipes can be of porous clay, whereas the watering hoses are riddled with holes or made of porous material, in surface drip irrigation. In these applications, the first approach consists of assuming that the flow concerns a pure fluid (as in a microfiltration system operating at a very low species concentration), and that the wall's leakage depends only on the local pressure difference between both inner and outer sides of the wall.
Pierre Haldenwang, Pierrette Guichardon. Pressure runaway in a 2D plane channel with permeable walls submitted to pressure-dependent suction. European Journal of Mechanics - B/Fluids, 2011, 30 (2), pp.177-183. ⟨10.1016/j.euromechflu.2010.09.007⟩. ⟨hal-00905831⟩
Dominique Morvan. Physical phenomena and length scales governing the behaviour of wildfires: a case for physical modelling. Fire Technology, 2011, 47 (2), pp.437-460. ⟨10.1007/s10694-010-0160-2⟩. ⟨hal-01022589⟩ Plus de détails...
This paper is an overview of the physical mechanisms and length scales governing the propagation of wildfires. One of the objectives is to identify the physical and mathematical constraints in the modelling of wildfires when using a "fully" physical approach. The literature highlights two regimes in the propagation of surface fires, i.e. wind-driven fires and plume-dominated fires, which are governed by radiation and convective heat transfer, respectively. This division leads to the identification of two governing length scales: the extinction length characterising the absorption of radiation by vegetation, and the integral turbulent length scale characterising the interaction between wind and canopy. Some numerical results published during the last decade using a fully physical approach are presented and discussed with a focus on the models FIRESTAR, FIRELES, FIRETEC and WFDS. Numerical simulations were compared with experimental data obtained at various scales, from laboratory to field fires in grassland and in Mediterranean shrubland. Some perspectives are presented concerning the potential coupling between physical fire models with mesoscale atmospheric models to study the impacts of wildfires at larger scale. Some of the topics on wildfire physical modelling that need further research are identified in the conclusions.
Dominique Morvan. Physical phenomena and length scales governing the behaviour of wildfires: a case for physical modelling. Fire Technology, 2011, 47 (2), pp.437-460. ⟨10.1007/s10694-010-0160-2⟩. ⟨hal-01022589⟩
Frédéric Schwander, Guillaume Chiavassa, Guido Ciraolo, Philippe Ghendrih, Livia Isoardi, et al.. Parallel shear flow instability in the tokamak edge. Journal of Nuclear Materials, 2011, 415 (1), pp.S601-S604. ⟨10.1016/j.jnucmat.2010.10.073⟩. ⟨hal-00848536⟩ Plus de détails...
The transition between the core and scrape-off layer of a tokamak corresponds to a marked momentum shear layer, owing to sheath acceleration on limiters which drives near-sonic flows along the plasma magnetic field in the scrape-off layer, and a parallel shear flow instability can possibly be triggered. The possibility of this instability driven by the velocity gradient is investigated numerically, using a minimum model of particle and parallel momentum transport in the edge of a tokamak, in a computational domain modelling a limiter plasma with background turbulence modelled as an effective diffusion. It is found that unstable regions can exist in the vicinity of a limiter, in agreement with experimental findings, when momentum radial transport - and therefore coupling between SOL and core flows - is sufficiently weak. Instability is reinforced by core rotation, and is found to be maximum downstream of the limiter (with respect to the core plasma flow).
Frédéric Schwander, Guillaume Chiavassa, Guido Ciraolo, Philippe Ghendrih, Livia Isoardi, et al.. Parallel shear flow instability in the tokamak edge. Journal of Nuclear Materials, 2011, 415 (1), pp.S601-S604. ⟨10.1016/j.jnucmat.2010.10.073⟩. ⟨hal-00848536⟩
A. Paredes, Eric Serre, Livia Isoardi, Guillaume Chiavassa, Guido Ciraolo, et al.. Boundary conditions at the limiter surface obtained in the modelling of plasma wall interaction with a penalization technique. Journal of Nuclear Materials, 2011, 415 (1), pp.S579-S583. ⟨10.1016/j.jnucmat.2010.12.247⟩. ⟨hal-00848532⟩ Plus de détails...
Isoardi et al. [1] recently proposed a penalization technique to model solid plasma facing components that treats a solid obstacle as a sink region corresponding to the strong plasma recombination in the solid state material. A major advantage of this approach is that it produces a system that can be solved in an obstacle free domain, thus allowing the use of powerful numerical algorithms. Such a technique implemented in a minimal transport model for ionic density and parallel momentum appeared to exhibit a Mach-1 transition at the boundary layer between the plasma presheath and the limiter region. In this paper, we reconsider this result by analysing the physics of detached plasmas that are governed both by strong recombination and plasma pressure decrease, as imposed by the penalization technique within the limiter region. The analysis provides a unique control parameter A=Γcsmi/ΠA=Γcsmi/Π (Γ being the parallel particles flux, cs the sound speed, mi the ionic mass and Π the total plasma pressure) that allows one to understand the results of the penalization technique for the Mach-1 transition.
A. Paredes, Eric Serre, Livia Isoardi, Guillaume Chiavassa, Guido Ciraolo, et al.. Boundary conditions at the limiter surface obtained in the modelling of plasma wall interaction with a penalization technique. Journal of Nuclear Materials, 2011, 415 (1), pp.S579-S583. ⟨10.1016/j.jnucmat.2010.12.247⟩. ⟨hal-00848532⟩
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Sofiane Meradji, et al.. Numerical simulation of coherent structures over plant canopy. Flow, Turbulence and Combustion, 2011, 86 (1), pp.89-111. ⟨10.1007/s10494-010-9294-z⟩. ⟨hal-01022574⟩ Plus de détails...
This paper reports large eddy simulations of the interaction between an atmospheric boundary layer and a canopy (representing a forest cover). The problem is studied for a homogeneous configuration representing the situation encountered above a continuous forest cover, as well as for a heterogeneous configuration representing the situation similar to an edge or a clearing in a forest. The numerical results reproduces correctly all the main characteristics of this flow as reported in the literature: the formation of a first generation of coherent structures aligned transversally with the wind flow direction, the reorganization and the deformation of these vortex tubes into horse-shoe structures. The results obtained when introducing a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest), are compared with the experimental data collected in a wind tunnel; here, the results confirm the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as the Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor.
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Sofiane Meradji, et al.. Numerical simulation of coherent structures over plant canopy. Flow, Turbulence and Combustion, 2011, 86 (1), pp.89-111. ⟨10.1007/s10494-010-9294-z⟩. ⟨hal-01022574⟩
Philippe Ghendrih, K. Bodi, Hugo Bufferand, Guillaume Chiavassa, Guido Ciraolo, et al.. Transition to supersonic flows in the edge plasma. Plasma Physics and Controlled Fusion, 2011, 53 (5), pp.054019. ⟨10.1088/0741-3335/53/5/054019⟩. ⟨hal-00848545⟩ Plus de détails...
With a proper choice of a single dimensionless control parameter one describes the transition between subsonic and supersonic flows as a bifurcation. The bifurcation point is characterized by specific properties of the control parameter: the control parameter has a vanishing derivative in space and takes the maximum possible value equal to 1. This method is then applied to the sheath plasma with constant temperatures, allowing one to recover the Bohm boundary condition as well as the location of the point where the bifurcation takes place. This analysis is extended to fronts, rarefaction waves and divertor plasmas. Two cases are found, those where departure from quasineutrality is mandatory to generate a maximum in the variation of the control parameter (sheath and fronts) and those where the physics of the quasineutral plasma can generate such a maximum (rarefaction waves and supersonic flow in divertors). The conditions that are required to recover the Bohm condition, when modelling the wall using the penalization technique, are also addressed and generalized.
Philippe Ghendrih, K. Bodi, Hugo Bufferand, Guillaume Chiavassa, Guido Ciraolo, et al.. Transition to supersonic flows in the edge plasma. Plasma Physics and Controlled Fusion, 2011, 53 (5), pp.054019. ⟨10.1088/0741-3335/53/5/054019⟩. ⟨hal-00848545⟩
Livia Isoardi, Hugo Bufferand, Guillaume Chiavassa, Guido Ciraolo, Frédéric Schwander, et al.. 2D modelling of electron and ion temperature in the plasma edge and SOL. Journal of Nuclear Materials, 2011, 415 (1), pp.S574-S578. ⟨10.1016/j.jnucmat.2010.12.318⟩. ⟨hal-00848528⟩ Plus de détails...
We are interested here in modelling the electron and ion temperature fields, Te and Ti respectively, in order to understand the main trends that govern the ratio Ti/Te that is being better documented in the SOL with RFA probes and . The experimental evidence gathered from several devices indicates that this temperature ratio significantly exceeds unity in most data sets that have been analysed, including measurements in the SOL of limiter devices like Tore Supra. Several issues of interest have been addressed with this version of the SOLEDGE-2D code. First, we have analysed the width of the SOL heat channels to the wall components and compared these values to analytical expressions. The key control mechanism of the width of the SOL heat channel is given by a balance between the sheath boundary conditions and the transverse transport. More advanced simulations address the interplay between the edge and SOL plasma allowing one to recover regimes with Ti/Te > 1.
Livia Isoardi, Hugo Bufferand, Guillaume Chiavassa, Guido Ciraolo, Frédéric Schwander, et al.. 2D modelling of electron and ion temperature in the plasma edge and SOL. Journal of Nuclear Materials, 2011, 415 (1), pp.S574-S578. ⟨10.1016/j.jnucmat.2010.12.318⟩. ⟨hal-00848528⟩
Evelyne Neau, Joan Escandell, Isabelle Raspo. A generalized reference state at constant volume for the prediction of phase equilibria from low pressure model parameters. Chemical Engineering Science, 2011, 66 (18), pp.4148-4156. ⟨10.1016/j.ces.2011.05.043⟩. ⟨hal-01023163⟩ Plus de détails...
This paper describes an EoS/GE approach based on cubic equations of state making reference to low pressure GE models derived from the lattice fluid theory of Guggenheim. The proposed method does not present the theoretical problems encountered with the literature reference states (infinite pressure of Huron-Vidal, zero pressure of Michelsen and constant packing fraction of Péneloux), namely the description of the alpha function with combinatorial terms derived from both the excess Gibbs energy model and the EoS. The main advantage of the proposed method is to successfully account for the size-asymmetry of mixture components and to improve the results obtained with the Wong-Sandler mixing rule. Comparisons are performed with the MHV1, LCVM and the original Wong-Sandler approach at infinite pressure.
Evelyne Neau, Joan Escandell, Isabelle Raspo. A generalized reference state at constant volume for the prediction of phase equilibria from low pressure model parameters. Chemical Engineering Science, 2011, 66 (18), pp.4148-4156. ⟨10.1016/j.ces.2011.05.043⟩. ⟨hal-01023163⟩
Guillaume Chiavassa, Bruno Lombard. Time domain numerical modeling of wave propagation in 2D heterogeneous porous media. Journal of Computational Physics, 2011, 230 (13), pp.5288-5309. ⟨10.1016/j.jcp.2011.03.030⟩. ⟨hal-00547008v2⟩ Plus de détails...
This paper deals with the numerical modeling of wave propagation in porous media described by Biot's theory. The viscous efforts between the fluid and the elastic skeleton are assumed to be a linear function of the relative velocity, which is valid in the low-frequency range. The coexistence of propagating fast compressional wave and shear wave, and of a diffusive slow compressional wave, makes numerical modeling tricky. To avoid restrictions on the time step, the Biot's system is splitted into two parts: the propagative part is discretized by a fourth-order ADER scheme, while the diffusive part is solved analytically. Near the material interfaces, a space-time mesh refinement is implemented to capture the small spatial scales related to the slow compressional wave. The jump conditions along the interfaces are discretized by an immersed interface method. Numerical experiments and comparisons with exact solutions confirm the accuracy of the numerical modeling. The efficiency of the approach is illustrated by simulations of multiple scattering.
Guillaume Chiavassa, Bruno Lombard. Time domain numerical modeling of wave propagation in 2D heterogeneous porous media. Journal of Computational Physics, 2011, 230 (13), pp.5288-5309. ⟨10.1016/j.jcp.2011.03.030⟩. ⟨hal-00547008v2⟩
K. Gavrilov, Dominique Morvan, Gilbert Accary, D.V. Lyubimov, Sofiane Meradji, et al.. Numerical modeling of coherent structures attendant on impurity propagation in the atmospheric boundary layer over a forest canopy. Fluid Dynamics / Izvestiya Akademii Nauk - Mekhanika Zhidkosti i Gaza, 2011, 46 (1), pp.138-147. ⟨10.1134/S0015462811010169⟩. ⟨hal-01030826⟩ Plus de détails...
Three-dimensional large eddy simulation is used to solve the problem for a homogeneous forest canopy. The development of the Kelvin-Helmholtz instability above the canopy leads to the formation of coherent structures in the atmosphere flow, which are reproduced in the calculations. The statistical characteristics of the flow obtained from the numerical modeling are compared with experimental data. The passive admixture transfer from the canopy to the clean atmosphere is studied for two cases, namely, for constant and variable coupled concentration of the impurity in the canopy.
K. Gavrilov, Dominique Morvan, Gilbert Accary, D.V. Lyubimov, Sofiane Meradji, et al.. Numerical modeling of coherent structures attendant on impurity propagation in the atmospheric boundary layer over a forest canopy. Fluid Dynamics / Izvestiya Akademii Nauk - Mekhanika Zhidkosti i Gaza, 2011, 46 (1), pp.138-147. ⟨10.1134/S0015462811010169⟩. ⟨hal-01030826⟩
Journal: Fluid Dynamics / Izvestiya Akademii Nauk - Mekhanika Zhidkosti i Gaza
Guilhem Dif-Pradalier, J Gunn, Guido Ciraolo, C S Chang, Guillaume Chiavassa, et al.. The Mistral base case to validate kinetic and fluid turbulence transport codes of the edge and SOL plasmas. Journal of Nuclear Materials, 2011, 415, ⟨10.1016/j.jnucmat.2010.12.035⟩. ⟨cea-01468372⟩ Plus de détails...
Experimental data from the Tore Supra experiments are extrapolated in the SOL and edge to investigate the Kelvin–Helmholtz instability. The linear analysis indicates that a large part of the SOL is rather unstable. The effort is part of the setup of the Mistral base case that is organised to validate the codes and address new issues on turbulent edges, including the comparison of kinetic and fluid modelling in the edge plasma.
Guilhem Dif-Pradalier, J Gunn, Guido Ciraolo, C S Chang, Guillaume Chiavassa, et al.. The Mistral base case to validate kinetic and fluid turbulence transport codes of the edge and SOL plasmas. Journal of Nuclear Materials, 2011, 415, ⟨10.1016/j.jnucmat.2010.12.035⟩. ⟨cea-01468372⟩
Dominique Morvan, Chad Hoffman, Francisco Rega, William Mell. Numerical simulation of the interaction between two fire fronts in grassland and shrubland. Fire Safety Journal, 2011, 46 (8), pp.469-479. ⟨10.1016/j.firesaf.2011.07.008⟩. ⟨hal-01022562⟩ Plus de détails...
The objective of this paper was to evaluate the potential for fully physical fire models to simulate the interactions between two converging fire fronts (a head fire and a back fire), in conditions similar to those encountered during suppression fire operations. The simulations were carried out using two fully physical models: FIRESTAR, in two dimensions, and Wildland Fire Dynamics Simulator, in three dimensions. Each modelling approach numerically solves a set of balance equations (mass, momentum, energy, etc.) governing the behaviour of the coupled system formed by the vegetation and the surrounding atmosphere. Two fuel profiles were tested: homogeneous grassland similar to landscapes in Australia and a shrubland representative of Mediterranean landscape (garrigue). Results from the two-dimensional and three-dimensional simulations were used to investigate how the two fire fronts interact together and mutually modify, or not, their own behaviour before merging. The results of these simulations showed that the merging of two fire fronts can result in a quick increase in fire-line intensity or in flame height. We concluded that physics-based simulations do reproduce reasonable and expected head- and back-fire interactions, but more work is needed to further understand the accuracy of such predictions.
Dominique Morvan, Chad Hoffman, Francisco Rega, William Mell. Numerical simulation of the interaction between two fire fronts in grassland and shrubland. Fire Safety Journal, 2011, 46 (8), pp.469-479. ⟨10.1016/j.firesaf.2011.07.008⟩. ⟨hal-01022562⟩
Guillaume Chiavassa, Hugo Bufferand, Guido Ciraolo, Philippe Ghendrih, Hervé Guillard, et al.. Parallel expansion of density bursts. Journal of Nuclear Materials, 2011, 415 (1), pp.S613-S616. ⟨10.1016/j.jnucmat.2010.10.086⟩. ⟨hal-00848522⟩ Plus de détails...
Evidence of poloidally localized cross-field transport in experiments and theoretical analysis of turbulence transport governs the onset of parallel transport towards equilibrium. When cross-field transport appears in bursts, both for ELM relaxation events and microturbulence, the parallel transport of particles is shown to generate fronts that propagate with supersonic velocities. It is shown that after a short transient the density structure is no longer monotonic and that the two fronts (one co, the other counter the magnetic field) are independent. Furthermore, the time trace of the particle flux at a given location is characterized by a sharp rise followed by a longer time scale relaxation. Comparing the time delay and magnitude of the density burst at two locations allows to estimate the magnitude and the location of the generation of the front.
Guillaume Chiavassa, Hugo Bufferand, Guido Ciraolo, Philippe Ghendrih, Hervé Guillard, et al.. Parallel expansion of density bursts. Journal of Nuclear Materials, 2011, 415 (1), pp.S613-S616. ⟨10.1016/j.jnucmat.2010.10.086⟩. ⟨hal-00848522⟩
Jérôme Julien, Mihail Garajeu, Jean-Claude Michel. A semi-analytical model for the behavior of saturated viscoplastic materials containing two populations of voids of different sizes. International Journal of Solids and Structures, 2011, 48 (10), pp.1485-1498. ⟨10.1016/j.ijsolstr.2011.01.031⟩. ⟨hal-00583378⟩ Plus de détails...
This paper presents a micromechanical model for a porous viscoplastic material containing two populations of pressurized voids of different sizes. Three scales are distinguished: the microscopic scale (corresponding to the size of the small voids), the mesoscopic scale (corresponding to the size of the large voids) and the macroscopic scale. It is assumed that the first homogenization step is performed at the microscopic scale, and, at the mesoscopic scale, the matrix is taken to be homogeneous and compressible. At the mesoscopic scale, the second homogenization step, on which the present study focuses, is based on a simplified representative volume element: a hollow sphere containing a pressurized void surrounded by a nonlinear viscoplastic compressible matrix. The nonlinear behavior of the matrix, which is expressed using the results obtained in the first homogenization step, is approached using a modified secant linearization procedure involving the discretization of the hollow sphere into concentric layers. Each layer has uniform secant moduli. The predictions of the model are compared with the more accurate numerical results obtained using the finite element method. Good agreement is found to exist with all the macroscopic stress triaxialities and all the porosity and nonlinearity values studied.
Jérôme Julien, Mihail Garajeu, Jean-Claude Michel. A semi-analytical model for the behavior of saturated viscoplastic materials containing two populations of voids of different sizes. International Journal of Solids and Structures, 2011, 48 (10), pp.1485-1498. ⟨10.1016/j.ijsolstr.2011.01.031⟩. ⟨hal-00583378⟩
Journal: International Journal of Solids and Structures
Hugo Bufferand, Guido Ciraolo, Livia Isoardi, Guillaume Chiavassa, Frédéric Schwander, et al.. Applications of SOLEDGE-2D code to complex SOL configurations and analysis of Mach probe measurements. Journal of Nuclear Materials, 2011, 415 (1), pp.S589-S592. ⟨10.1016/j.jnucmat.2010.11.037⟩. ⟨hal-00848483⟩ Plus de détails...
A series of experiments dedicated to the determination of the ballooning nature of the edge and SOL transport has been achieved on Tore Supra and , proposing a quantitative characterization of the radial flux that enters the SOL. The aim of this paper is to back up the interpretation of these probe flow measurements making use of SOLEDGE-2D code. In particular, this fluid code allows one to study density and parallel momentum transport in a 2D geometry including edge and SOL region. Moreover, thanks to an appropriate numerical technique recently proposed and , SOLEDGE-2D code is also able to deal with a complex geometry of plasma facing components including main and secondary limiters.
Hugo Bufferand, Guido Ciraolo, Livia Isoardi, Guillaume Chiavassa, Frédéric Schwander, et al.. Applications of SOLEDGE-2D code to complex SOL configurations and analysis of Mach probe measurements. Journal of Nuclear Materials, 2011, 415 (1), pp.S589-S592. ⟨10.1016/j.jnucmat.2010.11.037⟩. ⟨hal-00848483⟩
Hugo Bufferand, Guido Ciraolo, Livia Isoardi, Guillaume Chiavassa, Frédéric Schwander, et al.. Applications of SOLEDGE-2D code to complex SOL configurations and analysis of Mach probe measurements. Journal of Nuclear Materials, 2011, 415 (1), pp.S589-S592. ⟨10.1016/j.jnucmat.2010.11.037⟩. ⟨hal-00848483⟩ Plus de détails...
A series of experiments dedicated to the determination of the ballooning nature of the edge and SOL transport has been achieved on Tore Supra and , proposing a quantitative characterization of the radial flux that enters the SOL. The aim of this paper is to back up the interpretation of these probe flow measurements making use of SOLEDGE-2D code. In particular, this fluid code allows one to study density and parallel momentum transport in a 2D geometry including edge and SOL region. Moreover, thanks to an appropriate numerical technique recently proposed and , SOLEDGE-2D code is also able to deal with a complex geometry of plasma facing components including main and secondary limiters.
Hugo Bufferand, Guido Ciraolo, Livia Isoardi, Guillaume Chiavassa, Frédéric Schwander, et al.. Applications of SOLEDGE-2D code to complex SOL configurations and analysis of Mach probe measurements. Journal of Nuclear Materials, 2011, 415 (1), pp.S589-S592. ⟨10.1016/j.jnucmat.2010.11.037⟩. ⟨hal-00848483⟩
Colette Nicoli, Pierre Haldenwang. A resonant response of self-pulsating spray-flame submitted to acoustic wave. Combustion Science and Technology, 2010, 182 (4-6), pp.559-573. ⟨10.1080/00102200903465915⟩. ⟨hal-00907320⟩ Plus de détails...
Recently, experiments and theoretical investigations have shown that spray flame can exhibit oscillatory regimes for standard set of parameters. Theoretical and numerical investigations on flame propagation in two-phase premixtures have put forward an intrinsic (and robust) mechanism based on the interaction between the locus where droplets vaporize and the reaction zone. This mechanism invokes neither droplet inertia (very small droplets are studied) nor differential diffusive effects (pulsations take place for unity Lewis number, too). Self-oscillations of spray-flame occur as in a supercritical Hopf bifurcation, controlled by Zeldovich number (Ze, the reduced activation energy), the onset threshold being on the order of (Ze)c ≈ 10. The issue addressed in this contribution is whether acoustic wave and self-pulsating spray-flame can interact. This study was carried out in the open-loop context: a spray-flame was submitted to small amplitude fluctuations of pressure; the gain toward acoustics was found as depending on Zeldovich number because energy transfer is found magnified in the case of a close-frequency fit between acoustic resonator and natural spray-flame oscillations. Moreover, energy transfer is found as of resonant type.
Colette Nicoli, Pierre Haldenwang. A resonant response of self-pulsating spray-flame submitted to acoustic wave. Combustion Science and Technology, 2010, 182 (4-6), pp.559-573. ⟨10.1080/00102200903465915⟩. ⟨hal-00907320⟩
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩ Plus de détails...
This paper deals with the numerical simulation (using a LES approach) of the interaction between an atmospheric boundary layer (ABL) and a canopy, representing a forest cover. This problem was studied for a homogeneous configuration representing the situation encountered above a continuous forest cover, and a heterogeneous configuration representing the situation similar to an edge or a clearing in a forest. The numerical results, reproduced correctly all the main characteristics of this flow, as reported in the literature: the formation of a first generation of coherent structures aligned transversally from the wind flow direction, the reorganisation and the deformation of these vortex tubes to horse shoe structures. The results obtained, introducing a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest), were compared with experimental data collected in a wind tunnel. The results confirmed the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as an Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor.
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩
Evelyne Neau, Joan Escandell, Christophe Nicolas. Modeling of highly nonideal systems: 1. A generalized version of the NRTL equation for the description of low-pressure equilibria. Industrial and engineering chemistry research, 2010, 49 (16), pp.7580-7588. ⟨10.1021/ie100121c⟩. ⟨hal-01025255⟩ Plus de détails...
The topic of the present work is the development of a simple model for the description of phase equilibria occurring in nonideal systems, such as those containing size-asymmetric components or mixtures made of polar or associating compounds with hydrocarbons, that are capable of strong demixing. The generalized NRTL model presented in this first part derives from the lattice two-fluid theory and differs from the original model by considering the size asymmetry of mixture components; results obtained for the modeling of phase equilibria in hydrocarbon, polar, and highly immiscible systems are compared with other literature models, such as the van Laar, NRTL, and UNIQUAC models. In the second part of this work, this model is associated with the Peng−Robinson EoS using the EoS/GE approach based on a generalized reference state, and a new group contribution is proposed for the prediction of the binary interaction parameters.
Evelyne Neau, Joan Escandell, Christophe Nicolas. Modeling of highly nonideal systems: 1. A generalized version of the NRTL equation for the description of low-pressure equilibria. Industrial and engineering chemistry research, 2010, 49 (16), pp.7580-7588. ⟨10.1021/ie100121c⟩. ⟨hal-01025255⟩
Journal: Industrial and engineering chemistry research
Mounir Alliche, Pierre Haldenwang, Salah Chikh. Extinction conditions of a premixed flame in a channel. Combustion and Flame, 2010, 157 (6), pp.1060-1070. ⟨10.1016/j.combustflame.2010.02.006⟩. ⟨hal-00907298⟩ Plus de détails...
A local refinement method is used to numerically predict the propagation and extinction conditions of a premixed flame in a channel considering a thermodiffusive model. A local refinement method is employed because of the numerous length scales that characterize this phenomenon. The time integration is self adaptive and the solution is based on a multigrid method using a zonal mesh refinement in the flame reaction zone. The objective is to determine the conditions of extinction which are characterized by the flame structure and its properties. We are interested in the following properties: the curvature of the flame, its maximum temperature, its speed of propagation and the distance separating the flame from the wall. We analyze the influence of heat losses at the wall through the thermal conductivity of the wall and the nature of the fuel characterized by the Lewis number of the mixture. This investigation allows us to identify three propagation regimes according to heat losses at the wall and to the channel radius. The results show that there is an intermediate value of the radius for which the flame can bend and propagate provided that its curvature does not exceed a certain limit value. Indeed, small values of the radius will choke the flame and extinguish it. The extinction occurs if the flame curvature becomes too small. Furthermore, this study allows us to predict the limiting values of the heat loss coefficient at extinction as well as the critical value of the channel radius above which the premixed flame may propagate without extinction. A dead zone of length 2-4 times the flame thickness appears between the flame and the wall for a Lewis number (Le) between 0.8 and 2. For small values of Le, local extinctions are observed.
Mounir Alliche, Pierre Haldenwang, Salah Chikh. Extinction conditions of a premixed flame in a channel. Combustion and Flame, 2010, 157 (6), pp.1060-1070. ⟨10.1016/j.combustflame.2010.02.006⟩. ⟨hal-00907298⟩
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩ Plus de détails...
Concentration polarization affects numerous systems of membrane separation, and combined with osmosis, it can cause substantial reductions in permeation. We establish an exact solution to the conservation law of a solute advected by Berman flow. This flow is characteristic of reverse osmosis or nanofiltration. The resulting concentration polarization is then combined with the osmosis (counter-) effect. For large Péclet number of permeation, it yields a rigorous support to the semi-empirical "film" model, and accounts for the limit flux phenomenon. The main results are summarized in a simple diagram that relates three different Péclet numbers, and show that polarization combined with osmosis can withstand operating pressure almost totally.
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩
Journal: International Journal of Heat and Mass Transfer
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩ Plus de détails...
This paper deals with the numerical simulation (using a LES approach) of the interaction between an atmospheric boundary layer (ABL) and a canopy, representing a forest cover. This problem was studied for a homogeneous configuration representing the situation encountered above a continuous forest cover, and a heterogeneous configuration representing the situation similar to an edge or a clearing in a forest. The numerical results, reproduced correctly all the main characteristics of this flow, as reported in the literature: the formation of a first generation of coherent structures aligned transversally from the wind flow direction, the reorganisation and the deformation of these vortex tubes to horse shoe structures. The results obtained, introducing a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest), were compared with experimental data collected in a wind tunnel. The results confirmed the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as an Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor.
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩
Evelyne Neau, Joan Escandell, Christophe Nicolas. Modeling of highly nonideal systems: 2. Prediction of high pressure phase equilibria with the group contribution NRTL-PR EoS. Industrial and engineering chemistry research, 2010, 49 (16), pp.7589-7596. ⟨10.1021/ie101266x⟩. ⟨hal-01025263⟩ Plus de détails...
The purpose of this study is to propose a simple cubic equation of state for the prediction of phase equilibria in highly non ideal systems. The NRTL-PR equation of state is based on the association of the Peng−Robinson EoS and the generalized NRTL model developed in the first part of this work. This model, which derives from the lattice two-fluid theory, was specially developed to take account for the differences in size and shape between mixture components. The main advantage of the resulting NRTL-PR equation of state is to yield a simple and predictive model, depending on very few interaction parameters. In addition, it also allows satisfactory predictions of excess enthalpies, liquid−vapor and liquid−liquid equilibria occurring in mixtures formed by very asymmetric compounds, such as hydrocarbons, water, and ethylene glycols.
Evelyne Neau, Joan Escandell, Christophe Nicolas. Modeling of highly nonideal systems: 2. Prediction of high pressure phase equilibria with the group contribution NRTL-PR EoS. Industrial and engineering chemistry research, 2010, 49 (16), pp.7589-7596. ⟨10.1021/ie101266x⟩. ⟨hal-01025263⟩
Journal: Industrial and engineering chemistry research
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩ Plus de détails...
This paper deals with the numerical simulation (using a LES approach) of the interaction between an atmospheric boundary layer (ABL) and a canopy, representing a forest cover. This problem was studied for a homogeneous configuration representing the situation encountered above a continuous forest cover, and a heterogeneous configuration representing the situation similar to an edge or a clearing in a forest. The numerical results, reproduced correctly all the main characteristics of this flow, as reported in the literature: the formation of a first generation of coherent structures aligned transversally from the wind flow direction, the reorganisation and the deformation of these vortex tubes to horse shoe structures. The results obtained, introducing a discontinuity in the canopy (reproducing a clearing or a fuel break in a forest), were compared with experimental data collected in a wind tunnel. The results confirmed the existence of a strong turbulence activity inside the canopy at a distance equal to 8 times the height of the canopy, referenced in the literature as an Enhance Gust Zone (EGZ) characterized by a local peak of the skewness factor.
Konstantin Gavrilov, Gilbert Accary, Dominique Morvan, Dimitry Lyubimov, Oleg A Bessonov, et al.. Large eddy simulation of coherent structures over forest canopy. Deville M.; Lê T-H.; Sagaut P. Turbulence and Interactions: Proceedings the TI 2009 conference, Springer, pp.143-149, 2010, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 9783642141386. ⟨10.1007/978-3-642-14139-3_17⟩. ⟨hal-01024672⟩
Дмитрий Викторович Любимов, Константин Алексеевич Гаврилов, Dominique Morvan, Gilbert Accary, Sofiane Meradji, et al.. Численное моделирование когерентных структур при распростра-нении примеси в атмосферном пограничном слое над лесным пологом. Вычислительная механика сплошных сред, 2010, 3 (2), pp.34--45. ⟨hal-01291552⟩ Plus de détails...
D Morvan, Sofiane Meradji, G Accary. Physical modelling of fire spread in grasslands. Fire Safety Journal, 2009, 44 (1), pp.50--61. ⟨hal-01291553⟩ Plus de détails...
Livia Isoardi, Guido Ciraolo, Guillaume Chiavassa, Pierre Haldenwang, Eric Serre, et al.. Modelling SOL flow pattern spreading in the edge plasma. Journal of Nuclear Materials, 2009, 390-391, pp.388-391. ⟨10.1016/j.jnucmat.2009.01.088⟩. ⟨hal-00848559⟩ Plus de détails...
The transition region between closed and open magnetic flux surfaces plays a crucial role for tokamak performances. Appropriate understanding of the edge region remains a major challenge owing to several open issues as momentum transport, turbulence overshoot or neutral penetration. We consider here a transport model system to investigate the propagation of parallel momentum from the SOL into the core plasma and vice-versa. The numerical results show that for small values of the radial diffusion coefficient, the density profile decays exponentially from the core to the SOL as predicted by 1D analytical solution. A spreading of the parallel momentum from the SOL to the core is observed, with the presence of non-zero velocities also in the regions far from the SOL. The effect of an imposed rotation of the core plasma is investigated as well as the dynamics of an overdensity imposed in the core plasma.
Livia Isoardi, Guido Ciraolo, Guillaume Chiavassa, Pierre Haldenwang, Eric Serre, et al.. Modelling SOL flow pattern spreading in the edge plasma. Journal of Nuclear Materials, 2009, 390-391, pp.388-391. ⟨10.1016/j.jnucmat.2009.01.088⟩. ⟨hal-00848559⟩
Livia Isoardi, Guido Ciraolo, Guillaume Chiavassa, Pierre Haldenwang, Eric Serre, et al.. Modelling SOL flow pattern spreading in the edge plasma. Journal of Nuclear Materials, 2009, 390-391, pp.388-391. ⟨10.1016/j.jnucmat.2009.01.088⟩. ⟨hal-00848559⟩ Plus de détails...
The transition region between closed and open magnetic flux surfaces plays a crucial role for tokamak performances. Appropriate understanding of the edge region remains a major challenge owing to several open issues as momentum transport, turbulence overshoot or neutral penetration. We consider here a transport model system to investigate the propagation of parallel momentum from the SOL into the core plasma and vice-versa. The numerical results show that for small values of the radial diffusion coefficient, the density profile decays exponentially from the core to the SOL as predicted by 1D analytical solution. A spreading of the parallel momentum from the SOL to the core is observed, with the presence of non-zero velocities also in the regions far from the SOL. The effect of an imposed rotation of the core plasma is investigated as well as the dynamics of an overdensity imposed in the core plasma.
Livia Isoardi, Guido Ciraolo, Guillaume Chiavassa, Pierre Haldenwang, Eric Serre, et al.. Modelling SOL flow pattern spreading in the edge plasma. Journal of Nuclear Materials, 2009, 390-391, pp.388-391. ⟨10.1016/j.jnucmat.2009.01.088⟩. ⟨hal-00848559⟩
Most of the models proposed in literature for binary diffusion coefficients of solids in supercritical fluids are restricted to infinite dilution; this can be explained by the fact that most of experimental data are performed in the dilute range. However some industrial processes, such as supercritical fluid separation, operate at finite concentration for complex mixtures. In this case, the concentration dependence of diffusion coefficients must be considered, especially near the upper critical endpoint (UCEP) where a strong decrease of diffusion coefficients was experimentally observed. In order to represent this slowing down, a modified version of the Darken equation was proposed in literature for naphthalene in supercritical carbon dioxide. In this paper, the conditions of application of such a modelling are investigated. In particular, we focus on the order of magnitude of the solubility of the solid and on the vicinity of the critical endpoint. Various equations proposed in literature for the modelling of the infinite dilution diffusion coefficients of the solutes are also compared. Ten binary mixtures of solids with supercritical carbon dioxide were considered for this purpose.
Isabelle Raspo, Christophe Nicolas, Evelyne Neau, Sofiane Meradji. Diffusion coefficients of solids in supercritical carbon dioxide: Modelling of near critical behaviour. Fluid Phase Equilibria, 2008, 263 (2), pp.214-222. ⟨10.1016/j.fluid.2007.09.025⟩. ⟨hal-01139192⟩
Mihail Garajeu, Pierre Suquet. On the influence of local fluctuations in volume fraction of constituents on the effective properties of nonlinear composites. Application to porous materials. Journal of the Mechanics and Physics of Solids, 2007, 55 (4), pp.842-878. ⟨10.1016/j.jmps.2006.09.005⟩. ⟨hal-00214721⟩ Plus de détails...
Composite materials often exhibit local fluctuations in the volume fraction of their individual constituents. This paper studies the influence of such small fluctuations on the effective properties of composites. A general asymptotic expansion of these properties in terms of powers of the amplitude of the fluctuations is given first. Then, this general result is applied to porous materials. As is well-known, the effective yield surface of ductile voided materials is accurately described by Gurson's criterion. Suitable extensions for viscoplastic solids have also been proposed. The question addressed in the present study pertains to nonuniform distributions of voids in a typical volume element or in other words to the presence of matrix-rich and pore-rich zones in the material. It is shown numerically and analytically that such deviations from a uniform distribution result in a weakening of the macroscopic carrying capacity of the material.
Mihail Garajeu, Pierre Suquet. On the influence of local fluctuations in volume fraction of constituents on the effective properties of nonlinear composites. Application to porous materials. Journal of the Mechanics and Physics of Solids, 2007, 55 (4), pp.842-878. ⟨10.1016/j.jmps.2006.09.005⟩. ⟨hal-00214721⟩
Journal: Journal of the Mechanics and Physics of Solids
D Morvan, Sofiane Meradji, G Accary. Wildfire behavior study in a Mediterranean pine stand using a physically based model. Combustion Science and Technology, 2007, 180 (2), pp.230--248. ⟨hal-01291554⟩ Plus de détails...
D Morvan, Sofiane Meradji, G Accary. Wildfire behavior study in a Mediterranean pine stand using a physically based model. Combustion Science and Technology, 2007, 180 (2), pp.230--248. ⟨hal-01291554⟩
Isabelle Raspo, Sofiane Meradji, Bernard Zappoli. Heterogeneous reaction induced by the piston effect in supercritical binary mixtures. Chemical Engineering Science, 2007, 62 (16), pp.4182-4192. ⟨10.1016/j.ces.2007.04.027⟩. ⟨hal-01139223⟩ Plus de détails...
It is now well established that the large compressibility of supercritical fluids is responsible for the strong enhancement of the thermo-acoustic heating, leading to the speeding up of the heat transport thanks to the piston effect instead of the expected slowing down. We show in this paper, through numerical simulations, that the hydrodynamics behavior of supercritical fluids also couples with the critical behavior of the solubility of solids to cause the release of a heterogeneous reaction at solid surfaces in dilute binary supercritical mixtures.
Isabelle Raspo, Sofiane Meradji, Bernard Zappoli. Heterogeneous reaction induced by the piston effect in supercritical binary mixtures. Chemical Engineering Science, 2007, 62 (16), pp.4182-4192. ⟨10.1016/j.ces.2007.04.027⟩. ⟨hal-01139223⟩
Christophe Nicolas, Evelyne Neau, Sofiane Meradji, Isabelle Raspo. The Sanchez-Lacombe lattice fluid model for the modeling of solids in supercritical fluids. Fluid Phase Equilibria, 2005, 232 (1-2), pp.219-229. ⟨10.1016/j.fluid.2005.03.015⟩. ⟨hal-00846093⟩ Plus de détails...
The Sanchez-Lacombe equation of state is known to describe the thermodynamic properties of molecular fluids of arbitrary size, especially polymer-solvent phase behavior. However, it is rarely used for modeling solid-supercritical fluid equilibria. In this work, it is shown that a proper estimation of the EoS characteristic parameters together with a thermodynamically consistent expression of fugacity coefficients allows a satisfactory correlation of the solubility of solids in the supercritical phase. Binary mixtures containing carbon dioxide, ethane, ethylene and xenon were considered for this purpose. In a first step, the consistency of experimental data was checked using variance analysis. Then, different mixing rules were considered and results compared with those obtained with the Peng-Robinson equation. Finally, the lower and upper boundaries of the solid-liquid-vapor regions (LCEP and UCEP) were also determined and compared with experimental values.
Christophe Nicolas, Evelyne Neau, Sofiane Meradji, Isabelle Raspo. The Sanchez-Lacombe lattice fluid model for the modeling of solids in supercritical fluids. Fluid Phase Equilibria, 2005, 232 (1-2), pp.219-229. ⟨10.1016/j.fluid.2005.03.015⟩. ⟨hal-00846093⟩
Christophe Nicolas, Evelyne Neau, Sofiane Meradji, Isabelle Raspo. The Sanchez-Lacombe lattice fluid model for the modeling of solids in supercritical fluids. Fluid Phase Equilibria, 2005, 232 (1-2), pp.219-229. ⟨10.1016/j.fluid.2005.03.015⟩. ⟨hal-00846093⟩ Plus de détails...
The Sanchez-Lacombe equation of state is known to describe the thermodynamic properties of molecular fluids of arbitrary size, especially polymer-solvent phase behavior. However, it is rarely used for modeling solid-supercritical fluid equilibria. In this work, it is shown that a proper estimation of the EoS characteristic parameters together with a thermodynamically consistent expression of fugacity coefficients allows a satisfactory correlation of the solubility of solids in the supercritical phase. Binary mixtures containing carbon dioxide, ethane, ethylene and xenon were considered for this purpose. In a first step, the consistency of experimental data was checked using variance analysis. Then, different mixing rules were considered and results compared with those obtained with the Peng-Robinson equation. Finally, the lower and upper boundaries of the solid-liquid-vapor regions (LCEP and UCEP) were also determined and compared with experimental values.
Christophe Nicolas, Evelyne Neau, Sofiane Meradji, Isabelle Raspo. The Sanchez-Lacombe lattice fluid model for the modeling of solids in supercritical fluids. Fluid Phase Equilibria, 2005, 232 (1-2), pp.219-229. ⟨10.1016/j.fluid.2005.03.015⟩. ⟨hal-00846093⟩
Eric Rigolot, Dominique Morvan. Evaluation de l'efficacité des coupures de combustible par deux approches: dires d'experts et modélisation. Forêt Méditerranéenne, 2003, 24 (4), pp.403-418. ⟨hal-02674268⟩ Plus de détails...
Eric Rigolot, Dominique Morvan. Evaluation de l'efficacité des coupures de combustible par deux approches: dires d'experts et modélisation. Forêt Méditerranéenne, 2003, 24 (4), pp.403-418. ⟨hal-02674268⟩
Isabelle Raspo, Sandrine Hugues, Eric Serre, Anthony Randriamampianina, Patrick Bontoux. Spectral projection methods for the simulation of complex three-dimensional rotating flows. Computers and Fluids, 2002, 31 (4-7), pp.745-767. ⟨hal-01023173⟩ Plus de détails...
Isabelle Raspo, Sandrine Hugues, Eric Serre, Anthony Randriamampianina, Patrick Bontoux. Spectral projection methods for the simulation of complex three-dimensional rotating flows. Computers and Fluids, 2002, 31 (4-7), pp.745-767. ⟨hal-01023173⟩
Eric Serre, Isabelle Raspo, Patrick Bontoux. High order accurate spectral approximation for Navier-Stokes problems. Nonlinear Analysis: Theory, Methods and Applications, 2001, 47 (6), pp.4257-4268. ⟨hal-01023116⟩ Plus de détails...
Eric Serre, Isabelle Raspo, Patrick Bontoux. High order accurate spectral approximation for Navier-Stokes problems. Nonlinear Analysis: Theory, Methods and Applications, 2001, 47 (6), pp.4257-4268. ⟨hal-01023116⟩
Journal: Nonlinear Analysis: Theory, Methods and Applications
Eric Serre, Sandrine Hugues, Emilia Crespo del Arco, Anthony Randriamampianina, Patrick Bontoux. Axisymmetric and three-dimensional instabilities in an Ekman boundary layer flow. International Journal of Heat and Fluid Flow, 2001, 22 (1), pp.82-93. ⟨hal-01023080⟩ Plus de détails...
Eric Serre, Sandrine Hugues, Emilia Crespo del Arco, Anthony Randriamampianina, Patrick Bontoux. Axisymmetric and three-dimensional instabilities in an Ekman boundary layer flow. International Journal of Heat and Fluid Flow, 2001, 22 (1), pp.82-93. ⟨hal-01023080⟩
Journal: International Journal of Heat and Fluid Flow
Eric Serre, Isabelle Raspo, Patrick Bontoux, Roger Peyret. Spectral solutions of the Navier-Stokes equations for rotating flow,. Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik, 2001, 81 (1), pp.533-536. ⟨hal-01023113⟩ Plus de détails...
Eric Serre, Isabelle Raspo, Patrick Bontoux, Roger Peyret. Spectral solutions of the Navier-Stokes equations for rotating flow,. Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik, 2001, 81 (1), pp.533-536. ⟨hal-01023113⟩
Journal: Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik
Laurent Avaullee, Evelyne Neau, Jean-Noël Jaubert. Thermodynamic modeling for petroleum fluids II. Prediction of PVT properties of oils and gases by fitting one or two parameters to the saturation pressures of reservoir fluids. Fluid Phase Equilibria, 1997, 139 (1-2), pp.171 - 203. ⟨10.1016/s0378-3812(97)00170-2⟩. ⟨hal-01705902⟩ Plus de détails...
Laurent Avaullee, Evelyne Neau, Jean-Noël Jaubert. Thermodynamic modeling for petroleum fluids II. Prediction of PVT properties of oils and gases by fitting one or two parameters to the saturation pressures of reservoir fluids. Fluid Phase Equilibria, 1997, 139 (1-2), pp.171 - 203. ⟨10.1016/s0378-3812(97)00170-2⟩. ⟨hal-01705902⟩
Laurent Avaullee, Laurent Trassy, Evelyne Neau, Jean Noël Jaubert. Thermodynamic modeling for petroleum fluids I. Equation of state and group contribution for the estimation of thermodynamic parameters of heavy hydrocarbons. Fluid Phase Equilibria, 1997, 139 (1-2), pp.155 - 170. ⟨10.1016/s0378-3812(97)00168-4⟩. ⟨hal-01705903⟩ Plus de détails...
Laurent Avaullee, Laurent Trassy, Evelyne Neau, Jean Noël Jaubert. Thermodynamic modeling for petroleum fluids I. Equation of state and group contribution for the estimation of thermodynamic parameters of heavy hydrocarbons. Fluid Phase Equilibria, 1997, 139 (1-2), pp.155 - 170. ⟨10.1016/s0378-3812(97)00168-4⟩. ⟨hal-01705903⟩
Jean-Noël Jaubert, Evelyne Neau, Laurent Avaullee, Georges Zaborowski. Characterization of Heavy Oils. 3. Prediction of Gas Injection Behavior: Swelling Test, Multicontact Test, Multiple-Contact Minimum Miscibility Pressure, and Multiple-Contact Minimum Miscibility Enrichment. Industrial and engineering chemistry research, 1995, 34 (11), pp.4016-4032. ⟨10.1021/ie00038a043⟩. ⟨hal-02937291⟩ Plus de détails...
Jean-Noeel Jaubert, Evelyne Neau. Characterization of Heavy Oils. 2. Definition of a Significant Characterizing Parameter To Ensure the Reliability of Predictive Methods for PVT Calculations. Industrial and engineering chemistry research, 1995, 34 (5), pp.1873-1881. ⟨10.1021/ie00044a039⟩. ⟨hal-02937290⟩ Plus de détails...
Jean-Noeel Jaubert, Evelyne Neau. Characterization of Heavy Oils. 2. Definition of a Significant Characterizing Parameter To Ensure the Reliability of Predictive Methods for PVT Calculations. Industrial and engineering chemistry research, 1995, 34 (5), pp.1873-1881. ⟨10.1021/ie00044a039⟩. ⟨hal-02937290⟩
Journal: Industrial and engineering chemistry research
Jean-Noeel Jaubert, Evelyne Neau. Characterization of Heavy Oils. 2. Definition of a Significant Characterizing Parameter To Ensure the Reliability of Predictive Methods for PVT Calculations. Industrial and engineering chemistry research, 1995, 34 (5), pp.1873 - 1881. ⟨10.1021/ie00044a039⟩. ⟨hal-01703515⟩ Plus de détails...
Jean-Noeel Jaubert, Evelyne Neau. Characterization of Heavy Oils. 2. Definition of a Significant Characterizing Parameter To Ensure the Reliability of Predictive Methods for PVT Calculations. Industrial and engineering chemistry research, 1995, 34 (5), pp.1873 - 1881. ⟨10.1021/ie00044a039⟩. ⟨hal-01703515⟩
Journal: Industrial and engineering chemistry research
Jean-Noeel Jaubert, Evelyne Neau, Andre Peneloux, Catherine Fressigné, Alain Fuchs. Pressure, Volume, and Temperature Calculations on an Indonesian Crude Oil Using Detailed NMR Analysis or a Predictive Method To Assess the Properties of the Heavy Fractions. Industrial and engineering chemistry research, 1995, 34 (2), pp.640-655. ⟨10.1021/ie00041a026⟩. ⟨hal-02937289⟩ Plus de détails...
Jean-Noeel Jaubert, Evelyne Neau, Andre Peneloux, Catherine Fressigné, Alain Fuchs. Pressure, Volume, and Temperature Calculations on an Indonesian Crude Oil Using Detailed NMR Analysis or a Predictive Method To Assess the Properties of the Heavy Fractions. Industrial and engineering chemistry research, 1995, 34 (2), pp.640-655. ⟨10.1021/ie00041a026⟩. ⟨hal-02937289⟩
Journal: Industrial and engineering chemistry research
Jean-Noeel Jaubert, Evelyne Neau, Andre Peneloux, Catherine Fressigné, Alain Fuchs. Pressure, Volume, and Temperature Calculations on an Indonesian Crude Oil Using Detailed NMR Analysis or a Predictive Method To Assess the Properties of the Heavy Fractions. Industrial and engineering chemistry research, 1995, 34 (2), pp.640-655. ⟨10.1021/ie00041a026⟩. ⟨hal-01703512⟩ Plus de détails...
Jean-Noeel Jaubert, Evelyne Neau, Andre Peneloux, Catherine Fressigné, Alain Fuchs. Pressure, Volume, and Temperature Calculations on an Indonesian Crude Oil Using Detailed NMR Analysis or a Predictive Method To Assess the Properties of the Heavy Fractions. Industrial and engineering chemistry research, 1995, 34 (2), pp.640-655. ⟨10.1021/ie00041a026⟩. ⟨hal-01703512⟩
Journal: Industrial and engineering chemistry research
Marek Rogalski, Louis Schuffenecker, Evelyne Neau, Jean-Noël Jaubert, Jacques Jose. Characterization of highly boiling hydrocarbons with very low pressure data. Fluid Phase Equilibria, 1993, 87 (1), pp.89 - 98. ⟨10.1016/0378-3812(93)85019-i⟩. ⟨hal-02937288⟩ Plus de détails...
Evelyne Neau, Jean-Noël Jaubert, Marek Rogalski. Characterization of heavy oils. Industrial and engineering chemistry research, 1993, 32 (6), pp.1196 - 1203. ⟨10.1021/ie00018a027⟩. ⟨hal-01705918⟩ Plus de détails...
