Direct and Large Eddy Simulation of Stratified Homogeneous Shear Flows

Abstract

An overview is given on direct numerical simulations and on large eddy simulations of homogeneous turbulence under the impact of shear and stable stratification. We describe the methods used and report on the results of various studies. In particular, the vortex structure of turbulent motions is discussed. Moreover, the dynamics of statistical mean quantities are investigated. The mean variances are compared with experimental data. The turbulent diffusivity tensor for passive species in a stratified shear flow is computed. Moreover, a simple model is described which allows us to estimate the vertical diffusivities for heat and momentum for such flows when the vertical velocity variance or the dissipation rate are known.