Modelling the Dissipation Equation in Supersonic Turbulent Mixing Layers with High Density Gradients

In this work, the ability of a ke model, to compute mixing layers with significant density gradients, is discussed. It is shown that as in boundary layers, deficiencies appear for compressible flows, even if the ke model is improved by compressibility corrections. A modification of the sige coefficient is proposed to compute efficiently compressible mixing layers with high density variations. This new formulation leads to a separate modelling of the subsonic and supersonic effects. The results are presented on mixing layer computations with density ratios between 1/7 (velocity/density co-gradients) and 7 (velocity/density cross-gradients), and the convective Mach number evolves from 0.3 to 1. They show a clear improvement of the capability of the ke model to accurately compute high speed mixing layers