Section: New Results

Turbulence models

Participants : Alain Dervieux, Bruno Koobus [University of Montpellier 2] , Emmanuelle Itam [University of Montpellier 2] , Marianna Braza [CNRS-IMFT at Toulouse] , Stephen Wornom [Lemma] , Bruno Sainte-Rose [Lemma] .

The purpose of our work in hybrid RANS/LES is to develop new approaches for industrial applications of LES-based analyses. In the applications targetted (aeronautics, hydraulics), the Reynolds number can be as high as several tenth millions, far too high for pure LES models. However, certain regions in the flow can be better predicted with LES than with usual statistical RANS (Reynolds averaged Navier-Stokes) models. These are mainly vortical separated regions as assumed in one of the most popular hybrid model, the hybrid Detached Eddy Simulation model. Here, “hybrid” means that a blending is applied between LES and RANS. An important difference between a real life flow and a wind tunnel or basin is that the turbulence of the flow upstream of each body is not well known.

This year, we have continued the evaluation of a dynamic formulation of Piomelli-Germano type for the Variational-multiscale model. We have also modified the integration of the boundary layer by adding the so-called Menter correction imposing the Bradshaw law. We have studied these improvements on multiple-body flows. An emblematic case is the interaction between two parallel cylinders, one being in the wake of the other. A flow around a space probe at high Reynolds number is also studied [18] , [17] .