Turbulent Prandtl number and characteristic length scales in stably stratified flows: steady-state analytical solutions

On the turbulent Prandtl number in homogeneous stably stratified turbulence

In this paper, we derive a general relationship for the turbulent Prandtl number Pr t for homogeneous stably stratified turbulence from the turbulent kinetic energy and scalar variance equations. A formulation for the turbulent Prandtl number, Pr t , is developed in terms of a mixing length scale LM and an overturning length scale LE , the ratio of the mechanical (turbulent kinetic energy) deca...

Length scales of turbulence in stably stratified mixing layers

Turbulence resulting from Kelvin–Helmholtz instability in layers of localized stratification and shear is studied by means of direct numerical simulation. Our objective is to present a comprehensive description of the turbulence evolution in terms of simple, conceptual pictures of shear–buoyancy interaction that have been developed previously based on assumptions of spatially uniform stratifica...

Effect of the Prandtl number on a stratified turbulent wake

The effect of vortex pairing and Prandtl number on mixing in moderate Reynolds number stratified flows

Mixing resulting from Kelvin-Helmholtz instability is studied by direct numerical simulations for an intermediate Reynolds number in stratified flows where vortex pairing occurs. We investigate how the interaction of several billows changes the mixing properties. Simulations in a long domain show that only considering the interaction of two billows overestimates the amount of mixing and mixing ...

Prandtl number dependence of unsteady natural convection along a vertical plate in a stably stratified fluid

The Prandtl number dependence of unsteady laminar natural convection along an infinite vertical plate in a thermally stratified fluid is investigated. Flows are induced by an impulsive (step) change in plate temperature and by a suddenly imposed plate heat flux. Analytical solutions of the viscous equations of motion and thermodynamic energy are obtained for Prandtl numbers near unity by the me...