Generation of unsteady inflow conditions for compressible LES with a modified vortex method

Abstract

This article is to explore and modify vortex method to generate large eddy simulation( LES)inlet condition. In the modification,a density distribution of vortex which can avoid unreasonable vortex quantity in local place was used. The movement of vortex was controlled by Langevin equation,which mimics the active grid turbulence so as to generate an unsteady flow field which is more like the real turbulence. Knowing the results of Reynolds-averaged Navier-Stokes equations( RANS) and reconstructing the turbulence by vortex method( VM),the method was tested in the experimental channel. The statistical results of both inlet and outlet of the channel were given,which include the mean velocity,the vorticity and the Reynolds stress. By analyzing the generated field with the reference of direct numerical simulation( DNS) results and comparing with the results of original method,during the development of turbulence in the channel,it shows that the modified vortex method is viable and cost-effective for generating unsteady inflow condition for LES.