Document Type

Article

Publication Date

4-20-2006

Journal or Book Title

Physics of Fluids

Volume

18

Issue

4

First Page

045104

DOI

10.1063/1.2193472

Abstract

The energy evolution in buoyancy-generated turbulence subjected to shear depends on the gradient Richardson number Ri and the stratification number St, which is a ratio of the time scale of the initial buoyancy fluctuations to the time scale of the mean stratification. During an initial period, the flow state evolves as in the unsheared case. After this period, shear generates fluctuating velocity components for St=0.25, but it depletes the fluctuating vertical velocity component and temperature variance faster than in the unsheared case for St=4. Weak shear causes the kinetic and total energy to decrease faster than in the unsheared case, whereas strong shear adds more energy in comparison with the unsheared case. Energy increased with time in only one case considered (St=0.1 and Ri=0.04). When St>1, the nonlinearity of the flow does not become significant even when Ri is small. Thus, results from rapid distortion theory and direct numerical simulation compare well. In particular, the theory reproduces trends in the energy evolution for St>1.

Comments

The following article appeared in Physics of Fluids 18 (2006): 045104 and may be found at http://dx.doi.org/10.1063/1.2193472.

Rights

Copyright 2006 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

Copyright Owner

American Institute of Physics

Language

en

File Format

application/pdf

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