Numerical simulation of compressible mixing layers

Three-dimensional spatially developing compressible planar mixing layers are studied numerically for convective Mach number Mc = 0.4, 0.8 and 1.2. The present results for the flow-field structures, the mean velocity profiles, the mixing-layer growth rate and Reynolds stresses agree well with those of experiments and other numerical studies. The normalized growth rate decreases with increasing Mc. Shocklets are found to exist in the mixing layer at Mc = 1.2 and their formation mechanism shows good agreement with the scenario of flow around a bluff body. The effect of compressibility on the large-scale structures is stronger than that on the small-scale ones. The budget of the Reynolds-stress transport equations agree well with that from the temporal developing results. The magnitudes of most of the contributing terms in the budget reduce with increased compressibility effect except for the pressure-dilatation term which is very small.