Modeling of reactive multiphase flows

The aim of this research area is to develop unified modeling methods for multiphase reactive flows. This type of complex flow is found in a large number of practical applications. In rocket engines, for example, liquid oxygen is injected in the form of a liquid jet. This jet then undergoes a phase of intense destabilization and atomization, before evaporating and reacting with the surrounding hydrogen. The jet atomization process and the combustion of the dispersed phase resulting from this jet are generally treated separately, i.e. without any real coupling. In fact, no model exists that can represent both the two-phase aspect of the jet and the combustion of the dispersed phase. However, it is clear that injection, atomization, evaporation and combustion are strongly coupled phenomena: the release of intense heat in the flame necessarily influences the dynamics of the liquid jet, while the latter influences the position of the flame, and therefore the characteristics of combustion.
Beyond the space field, the simultaneous presence of liquid/gas interfaces and combustion zones, and more generally of multiple interfaces, can be found in numerous applications: transport (heat engines and in particular diesel engines), energy and the environment (industrial burners), but also the safety of 4th generation nuclear reactors (combustion of liquid or solid sodium in contact with air and water). Similar phenomena can be found in inertial confinement fusion problems. In each of these examples, an interface between two media is present, along with another transition zone, corresponding either to a flame, another moving material interface, or a laser absorption zone. The material interfaces considered here are not just the points of contact between the two phases: heat and mass exchanges are present through diffusion, combined with capillary and compressible effects.

Two types of approach have been developed to address this issue: 
  • A continuous approach, based on the resolution of Navier-Stokes-type equations (transverse axis with IUSTI's SHOC team)
  • A mesoscopic approach, based on the Boltzmann equation (transverse axis with ITC-TONIC).