Numerical validation of scaling laws for stratified turbulence
Pascale Garaud, Greg P. Chini, Laura Cope, Kasturi Shah, Colm-cille P. Caulfield
arXiv:2404.05896v1 Announce Type: cross
Abstract: Recent theoretical progress using multiscale asymptotic analysis has revealed various possible regimes of stratified turbulence. Notably, buoyancy transport can either be dominated by advection or diffusion, depending on the effective P’eclet number of the flow. Two types of asymptotic models have been proposed, which yield measurably different predictions for the characteristic vertical velocity and length scale of the turbulent eddies in both diffusive and non-diffusive regimes. The first, termed a `single-scale model’, is designed to describe flow structures having large horizontal and small vertical scales, while the second, termed a `multiscale model’, additionally incorporates flow features with small horizontal scales, and reduces to the single-scale model in their absence. By comparing predicted vertical velocity scaling laws with direct numerical simulation data, we show that the multiscale model correctly captures the properties of strongly stratified turbulence within spatiotemporally-intermittent turbulent patches. Meanwhile its single-scale reduction accurately describes the more orderly layer-like flow outside those patches.arXiv:2404.05896v1 Announce Type: cross
Abstract: Recent theoretical progress using multiscale asymptotic analysis has revealed various possible regimes of stratified turbulence. Notably, buoyancy transport can either be dominated by advection or diffusion, depending on the effective P’eclet number of the flow. Two types of asymptotic models have been proposed, which yield measurably different predictions for the characteristic vertical velocity and length scale of the turbulent eddies in both diffusive and non-diffusive regimes. The first, termed a `single-scale model’, is designed to describe flow structures having large horizontal and small vertical scales, while the second, termed a `multiscale model’, additionally incorporates flow features with small horizontal scales, and reduces to the single-scale model in their absence. By comparing predicted vertical velocity scaling laws with direct numerical simulation data, we show that the multiscale model correctly captures the properties of strongly stratified turbulence within spatiotemporally-intermittent turbulent patches. Meanwhile its single-scale reduction accurately describes the more orderly layer-like flow outside those patches.