Section: New Results

Fluid Turbulence

Hybrid RANS-LES models

Participants : Anca Belme [Tropics] , Alain Dervieux, Bruno Koobus [University of Montpellier 2] , Carine Moussaed [University of Montpellier 2] , Hilde Ouvrard [IMF-Toulouse] , Maria-Vittoria Salvetti [University of Pisa] , Stephen Wornom [Lemma] .

The purpose of our works in hybrid RANS/LES is to develop new approaches for industrial applications of LES-based analyses. In the foreseen applications (aeronautics, hydraulics), the Reynolds number can be as high as several tenth millions, a far too large number for pure LES models. However, certain regions in the flow can be much 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. The french-italian team has designed a novel type of hybrid model. This year, the new model has been adapted to very high Reynolds number. Our benchmark is the flow past a circular cylinder, an ECINADS test case. Reynolds number as high as 3 Millions could be passed with good prediction of main properties like mean drag, root mean square of lift fluctuation, base pressure.

Acoustics

Participants : Anca Belme [Tropics] , ILya Abalakin [IMM-Moscou] , Alain Dervieux [Tropics] , Alexandre Carabias.

A method for the simulation of aeroacoustics on the basis of these models has been designed and developed by a cooperation between the Computational Aeroacoustics Laboratory (CAL) of Intitute for Mathematical Modeling at Moscow and INRIA. Further applications has been developed by the Russian team from the two common numerical scheme, the Mixed-Element-Volume at sixth-order, and the quadratic reconstruction scheme. This year the cooperation is concentrated on the study by Alexandre Carabias of a new quadratic reconstruction scheme, which extends the one developed by Hilde Ouvrard and Ilya Abalakin. A second research topic was the calculation of acoustic propagation with unsteady mesh adaptation.