In addition to the very rich fundamental aspect, in particular turbulence, rotating flows in the presence of a thermal gradient cover a wide range of industrial and environmental applications, from turbomachinery to geophysics, the team is interested in flows and heat transfer in confined fluids. The overall aim is to identify the mechanisms responsible for the transition to turbulence.

Work carried out in recent years has focused on two specific configurations, in collaboration with laboratories with experimental rigs (AOPP, Oxford UK and BTU, Cottbus-Senftenberg Germany):

- baroclinic instability in a block-rotating cavity, with a radial temperature gradient perpendicular to the axis of rotation;

- strato-rotational instability in a Taylor-Couette geometry, with a positive vertical temperature gradient parallel to the axis of rotation, generating fluid stratification.

Studies are carried out using direct and large-scale numerical simulations, using calculation codes developed in the laboratory and based on high-precision numerical methods (spectral approximations and compact finite differences). The fluid is modeled either by the Boussinesq approximation or by the Low Mach Number approximation for large temperature differences. The high rotational speeds of the systems, the confinement which induces very thin three-dimensional boundary layers, and the coupling of the hydrodynamics with the thermal field require optimization of the numerical methods developed, including parallel computation.

A new project concerns the optimization of the secondary circuit used to cool the turbine disks in an aircraft engine under conditions close to actual operation. This requires, first and foremost, a better understanding of the strong coupling between the highly complex flow structures that develop in the inter-disc cavity of a high-pressure compressor, and heat transfer. We will take into account radiative effects as well as conductive exchanges between the solid parts and the fluid in order to establish a precise heat balance. The study will be carried out using direct numerical simulations, as well as large-scale simulations using a multi-domain code. The team also has many years' experience in simulating isothermal turbulent flows.

The team has recently developed a new approach to High-Performance Computing (HPC) in collaboration with LAMPS, University of Perpignan, France. The aim is to better adapt our calculation codes to the various specific problems encountered: geometric constraints on experimental benches, excessively long transient times, coexistence of very different spatio-temporal scales, etc.