Large-scale vortices in high-speed mixing layers

Abstract

The two-dimensional planar compressible mixing layers with Mc=0.4, 0.8, 1.2, and 1.4 are investigated numerically. The present results show that the mixing layer with high Mc is much more stable and expands very slowly. But there still exist large-scale vortex roll-up and pairings far from the upstream. The distance for the large-scale vortex development increases with Mc and can be effectively shortened by a strong inflow forcing. The asymmetry about the mixing layer center increases with increasing Mc. The difference of the growth rates based on different thickness definitions increases although they all decrease with Mc.