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Large-eddy simulations of stratified plane Couette flow using the anisotropic minimum-dissipation model

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Taylor, JR 

Abstract

jats:pThe anisotropic minimum-dissipation (AMD) model for large-eddy simulation (LES) has been recently developed, and here the model performance is examined in stratified plane Couette flow. To our knowledge, this is the first use of the AMD model for resolved LES of stratified wall-bounded flow. A comparison with previously published direct numerical simulations (DNS) provides insight into model and grid requirements. Prandtl numbers of Pr = 0.7–70 and a range of Richardson numbers show that the AMD LES performs well even with a strong stabilising buoyancy flux. We identify three new requirements for accurate LES of stratified wall-bounded flow. First, the LES must resolve the turbulent structures at the edge of the viscous sublayer in order to satisfy the Obukov length scale condition, Ls+&gt;200. Otherwise the LES solution may laminarise where the DNS solution remains turbulent. Second, the LES must have enough vertical grid resolution within the viscous and diffusive sublayers to resolve the wall fluxes. Third, the grid must be reasonably isotropic (vertical-to-horizontal grid aspect ratio &gt;0.25) at the edge of the sublayer and through the turbulent interior for the AMD LES to correctly simulate the scalar flux. When these model requirements are fulfilled, the AMD LES performs very well, producing vertical mean profiles, friction Reynolds numbers, and Nusselt numbers consistent with DNS solutions at significantly higher grid resolution.</jats:p>

Description

Keywords

4012 Fluid Mechanics and Thermal Engineering, 4007 Control Engineering, Mechatronics and Robotics, 40 Engineering

Journal Title

Physics of Fluids

Conference Name

Journal ISSN

1070-6631
1089-7666

Volume Title

30

Publisher

AIP Publishing
Sponsorship
Natural Environment Research Council (NE/N009746/1)