An Anisotropic Subgrid-Scale Parameterization for Large-Eddy Simulations of Stratified Turbulence
Abstract
Subgrid-scale (SGS) parameterizations in atmosphere and ocean models are often defined independently in
the horizontal and vertical directions because the grid spacing is not the same in these directions (anisotropic grids). In this
paper, we introduce a new anisotropic SGS model in large-eddy simulations (LES) of stratified turbulence based on hor izontal filtering of the equations of motion. Unlike the common horizontal SGS parameterizations in atmosphere and ocean
models, the vertical derivatives of the horizontal SGS fluxes are included in our anisotropic SGS scheme, and therefore
the horizontal and vertical SGS dissipation mechanisms are not disconnected in the newly developed model. Our
model is tested with two vertical grid spacings and various horizontal resolutions, where the horizontal grid spacing is
comparatively larger than that in the vertical. Our anisotropic LES model can successfully reproduce the results of
direct numerical simulations, while the computational cost is significantly reduced in the LES. We suggest the new
anisotropic SGS model as an alternative to current SGS parameterizations in atmosphere and ocean models, in which
the schemes for horizontal and vertical scales are often decoupled. The new SGS scheme may improve the dissipative
performance of atmosphere and ocean models without adding any backscatter or other energizing terms at small
horizontal scales.
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Cite this version of the work
Sina Khani, Michael L Waite
(2020).
An Anisotropic Subgrid-Scale Parameterization for Large-Eddy Simulations of Stratified Turbulence. UWSpace.
http://hdl.handle.net/10012/17656
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