DIRECT NUMERICAL-SIMULATION OF TURBULENT MIXING IN SHEAR FLOWS

This article considers one of the simplest shear flows-1D time-depende nt plane mixing layer. Under certain conditions, many more complicated flows are similar to it: time-independent plane mixing layer, initial portion of plane and round jets, initial mixing phase in cylindrical vortex, etc. This application was previously studied in a 2D approxima tion. In this computation the turbulence was treated as the result of random perturbations initially applied to the interface of two flows. Numerical simulation used a 2D EGAK code. The computational results we re interpreted using the version of semi-empirical turbulent theory wi th isotropic Reynolds tensor (model 1). This article continues the stu dies by Bakhrakh; in addition, a similar approach is implemented based on 3D simulation with the TREK method. The data interpretation uses t he version of semi-empirical theory with and without Reynolds tensor a nisotropy (models 1 and 2, respectively).