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An intercomparison of subgrid models for large‐eddy simulation of katabatic flows
Author(s) -
Smith Craig M.,
PortéAgel Fernando
Publication year - 2013
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2212
Subject(s) - large eddy simulation , buoyancy , scale model , grid , scale (ratio) , katabatic wind , scale invariance , geology , meteorology , statistical physics , mechanics , turbulence , mathematics , atmospheric sciences , physics , geodesy , statistics , engineering , quantum mechanics , aerospace engineering
We present an intercomparison of three subgrid‐scale ( SGS ) models for large‐eddy simulation ( LES ) of katabatic flows. The SGS closures we study include the Smagorinsky formulation, a scale‐invariant dynamic model, and a scale‐dependent dynamic model. Downslope fluxes of mass and buoyancy deficit are highly sensitive to SGS closure choice. Due to strong shear and strong stratification, the dynamic models show a reduction of the Smagorinsky coefficient near the surface relative to the Smagorinsky model. Furthermore, results from both scale‐dependent dynamic models suggest that the assumptions of scale invariance in the dynamic model are violated. We present a second set of experiments which focus on grid resolution requirements of eddy‐resolving simulations of drainage flows. Downslope buoyancy and mass flux predictions produced by the scale‐dependent dynamic model are more robust with respect to grid resolution and grid anisotropy than the scale‐invariant dynamic and Smagorinsky SGS models. Predictions of vertically integrated downvalley mass and buoyancy fluxes are more sensitive to vertical grid resolution than horizontal grid resolution.