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Numerical Simulation of Turbulent Convective Flow Over Wavy Terrain

Dörnbrack, A. and Schumann, U. (1993) Numerical Simulation of Turbulent Convective Flow Over Wavy Terrain. Boundary-Layer Meteorology, 65, pp. 323-355.

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Abstract

By means of a large-eddy simulation, the convective boundary layer is investigated for flows over wavy terrain. The lower surface varies sinusoidalty in the downstream direction while remaining constant in the other. Several cases are considered with amplitude 6 up to 0.15H and wavelength A of H to 8H, where H is the mean fluid-layer height. At the lower surface, the vertical heat flux is prescribed to be constant and the momentum flux is determined locally from the Monin-Obukhov relationship with a roughness length z<sub>0</sub> = 10<sup>-4</sup>H. The mean wind is varied between zero and 5w<sub>∗</sub>, where w<sub>∗</sub> is the convective velocity scale. After rather long times, the flow structure shows horizontal scales up to 4H, with a pattern similar to that over flat surfaces at corresponding shear friction. Weak mean wind destroys regular spatial structures induced by the surface undulation at zero mean wind. The surface heating suppresses mean-flow recirculation-regions even for steep surface waves. Short surface waves cause strong drag due to hydrostatic and dynamic pressure forces in addition to frictional drag. The pressure drag increases slowly with the mean velocity, and strongly with 6/H. The turbulence variances increase mainly in the lower half of the mixed layer for U/w<sub>∗</sub> > 2.

Item URL in elib:https://elib.dlr.de/31794/
Document Type:Article
Title:Numerical Simulation of Turbulent Convective Flow Over Wavy Terrain
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Dörnbrack, A.UNSPECIFIEDUNSPECIFIED
Schumann, U.UNSPECIFIEDUNSPECIFIED
Date:1993
Journal or Publication Title:Boundary-Layer Meteorology
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:65
Page Range:pp. 323-355
Status:Published
Keywords:convective boundary layer, wavy terrain, shear flow
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: DLR-Beauftragter, elib
Deposited On:02 Apr 2006
Last Modified:31 Jul 2019 19:17

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