LARGE EDDY SIMULATIONS OF ROUND FREE JETS USING EXPLICIT FILTERING WITH/WITHOUT DYNAMIC SMAGORINSKY MODEL

Abstract Large eddy simulations (LES) of round free jets at Mach number M  = 0.9 with Reynolds numbers over the range 2.5 × 10 3  ⩽  Re D  ⩽ 4 × 10 5 are performed using explicit selective/high-order filtering with or without dynamic Smagorinsky model (DSM). Features of the flows and of the turbulent kinetic energy budgets in the turbulent jets are reported. The contributions of molecular viscosity, filtering and DSM to energy dissipation are also presented. Using filtering alone, the results are independent of the filtering strength, and the effects of the Reynolds number on jet development are successfully calculated. Using DSM, the effective jet Reynolds number is found to be artificially decreased by the eddy viscosity. The results are also not appreciably modified when subgrid-scale kinetic energy is used. Moreover, unlike filtering which does not significantly affect the larger computed scales, the eddy viscosity is shown to dissipate energy through all the turbulent scales, in the same way as molecular viscosity at lower Reynolds numbers.