DOI: 10.1615/TSFP7
ASSESSMENT OF LARGE-EDDY SIMULATION BASED ON RELAXATION FILTERING: APPLICATION TO THE TAYLOR-GREEN VORTEX
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 .