Numerical Investigation of Stratified Turbulence

Abstract

In order to evaluate turbulence subgrid-scale models for stably stratified flows, we performed direct numerical simulations (DNS) of homogeneous stratified turbulence with large-scale horizontal forcing. In these simulations we found that energy dissipation is concentrated within thin layers of horizontal tagliatelle-like vortex sheets between large pancake-like structures. For large eddy simulation (LES), we use an implicit subgrid-scale model, based on the Adaptive Local Deconvolution Method (ALDM). Our analysis proves that the implicit turbulence modelALDMcorrectly predicts the turbulence energy budget and the energy spectra of stratified turbulence, even though dissipative structures are not resolved on the computational grid.