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RANS/LES COUPLING USING A FORCING TERM APPROACH

Younes Benarafa
CEA Grenoble DEN/DER/SSTH/LMDL 17, rue des martyrs 38054 Grenoble cedex 9, France

Frederic Ducros
CEA Grenoble DEN/DER/SSTH/LMDL 17, rue des martyrs 38054 Grenoble cedex 9, France

Pierre Sagaut
Institut Jean Le Rond D'Alembert, UMR 7190 Université Pierre et Marie Curie 4 place Jussieu 75005 Paris, France; Laboratoire de Mecanique, Modelisation et Procedes Propres UMR CNRS 7340 Aix-Marseille Universite IMT La Jetee, Technopole de Chateau-Gombert 38, rue Frederic Joliot-Curie 13451 Marseille Cedex 13, France

Abstract

In nuclear industry the relevant flows are often wall bounded, characterized by a high Reynolds number turbulence and a strong unsteadiness. In order to develop an advanced numerical modeling that takes into account these features while extending on a large enough spatial flow configuration to be relevant for industrial goals, we start focusing on a methodology of coupling based on the following idea: we want to couple regions where standard fine resolved LES is used with regions resolved in the framework of RANS/LES coupling. This latter is considered here as full 3D unsteady simulations providing reasonable and accurate numerical solution with an affordable computational effort when compared to standard RANS modeling. The paper is devoted to this RANS/LES coupling method, based on the application of a forcing term and provides results on a first validation test on a fully and very coarse mesh. All the computations of this study were performed with the TRIO_U code developed at CEA (French Atomic Center) Grenoble. The RANS/LES coupling method applied in this study ensures a mean profile as correct as the RANS computation and an improvement for the fluctuations profiles compared to LES on coarse grid without forcing term.