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Large-Eddy Simulation of the Up-slope Boundary Layer

Schumann, U. (1990) Large-Eddy Simulation of the Up-slope Boundary Layer. Quarterly Journal of the Royal Meteorological Society, 116, pp. 637-670. DOI: 10.1002/qj.49711649307.

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Official URL: http://www3.interscience.wiley.com/journal/113388514/home

Abstract

Large-eddy simulation (LES) is used to determine the turbulent structure of the steady-state up-slope boundary layer (UBL) which forms at a uniformly heated inclined or vertical plane surface below a stratified atmosphere at rest. At proper scales, the problem depends solely on the slope angle a and the surface roughness height z<sub>0</sub> a relative to a length scale H which is a function of stratification and surface heating. We cover 2° ≤ α ≤ 90° and 3 × 10<sup>-5</sup> ≤ z<sub>0</sub>/H ≤ 3 × 10<sup>-2</sup> by a series of LESs. Simulations using different grids show that the results are only weakly sensitive to truncation errors. the UBL approaches a steady-state mean-profile by slowly decaying oscillations; its frequency equals the Brunt-Väisälä frequency times sin α. In the LES, convergence towards steady state has been enforced by adjusting the fields according to integral steady-state conditions. For α ≤ 10°, a well-mixed layer is formed which causes a strong temperature inversion and strong down-slope flow at the outer edge of the UBL. Large-scale coherence is weak with some indications of cross-slope rolls for small inclination angles and longitudinal rolls for steep slopes. Several mean quantities have been tabulated as a function of slope angle and surface roughness and approximating power laws are given. the dependence of mean quantities on the slope angle is difficult to explain with simple models, but the influence of surface roughness closely follows earlier results.

Document Type:Article
Title:Large-Eddy Simulation of the Up-slope Boundary Layer
Authors:
AuthorsInstitution or Email of Authors
Schumann, U.UNSPECIFIED
Date:1990
Journal or Publication Title:Quarterly Journal of the Royal Meteorological Society
Volume:116
DOI:10.1002/qj.49711649307
Page Range:pp. 637-670
Status:Published
Keywords:Boundary Layer, Simulation
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Deposited By: elib DLR-Beauftragter
Deposited On:02 Apr 2006
Last Modified:12 Dec 2013 20:14

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