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ASSESSMENT OF LARGE-EDDY SIMULATION BASED ON RELAXATION FILTERING: APPLICATION TO THE TAYLOR-GREEN VORTEX

Dieter Fauconnier
Department of Flow, Heat and Combustion Mechanics Ghent University, St. Pietersnieuwstraat 41, 9000 Ghent, Belgium

Erik Dick
Dept. of Flow, Heat and Combustion Mechanics, University of Gent, St. Pietersnieuwstraat 41, 9000 Gent, Belgium

Christophe Bogey
Laboratoire de Mecanique des Fluides et d'Acoustique UMR CNRS 5509, Ecole Centrale de Lyon 69134 Ecully, France

Christophe Bailly
Laboratoire de Mecanique des Fluides et d'Acoustique UMR CNRS 5509, Ecole Centrale de Lyon 69134 Ecully, France

Resumo

Results obtained for a Taylor-Green vortex at a Reynolds number of 3000, using Large-Eddy Simulation (LES) based on Relaxation Filtering (RF), are presented in order to assess the quality of the RF-LES methodology. The RF is applied every time step to the velocity components, using a standard filters of orders k ≥ 4 at a fixed strength σ , to relax subgrid energy from scales at wave numbers close to the grid cut-off wave number. Various combinations of k and σ are considered, for k ranging from 4 to 14 and σ from 0.15 to 1. Error landscapes are obtained by comparing the 643 LES results, filtered in post-processing to an effective resolution of four points per wavelength, to 3843 Direct Numerical Simulation data, filtered at identical resolution. For filters of order k ≤ 6, the LES accuracy is found to be rather poor and varies significantly with the filtering strength σ . However, for higher order filters, i.e. for k > 6, the accuracy is good and nearly independent of the strength σ .