Spectra and distribution functions of stably stratified turbulence

Abstract

We examine homogeneous stably stratified turbulence both freely decaying and randomly forced cases. Our principal focus is the scale size distribution of the eddies and waves (spectra) comprising the flow. We also present results for the rate of decay for unforced flows. The tools used in both spectral and decay studies are direct numerical simulations (DNS), combined with elements of the statistical theory of turbulence. For situationally maintained flows, our results are consistent with spectra that are steeper than Kolmogorov at large scales but fair over into the normal isotropic inertial range at smaller scales. The DNS decay rate of freely decaying strongly stratified turbulence is consistent with t-1. For stratified flow, our simulations are consistent with a near equilibration between waves and vortical eddies. © 2010 Springer Science+Business Media B.V.