Large eddy simulation of compressible mixing layers

Large eddy simulations (LES) are performed to study spatially evolving compressible mixing layers at different convective Mach numbers. Two subgrid models are investigated : the dynamic Smagorinsky model and the dynamic mixed model. Simulations at the low convective Mach number of 0.16 are first performed. After an initial transient, the mean field and the Reynolds stress reach self-similar profiles and the peak values of the Reynolds stress components obtained through the two subgrid models are within the range of experimental and DNS results. Then, the convective Mach number is increased and simulations are performed at the higher convective Mach numbers of 0.5 and 1.1. The decrease of the growth rate and of the turbulence intensities with the convective Mach number is predicted. Results on the anisotropy and the decrease of the production and the pressure-strain are then presented. Isovorticity fields in a x − y plane are also studied.