Accession Number:

AD1081182

Title:

Numerical Simulation of Atmospheric Boundary Layer Flow over Battle Eld-Scale Complex Terrain: Surface Fluxes from Resolved and subgrid scales

Descriptive Note:

[Technical Report, Final Report]

Corporate Author:

University of Texas at Dallas

Personal Author(s):

• Anderson, William

Report Date:

2018-11-30

Pagination or Media Count:

18

Abstract:

The atmospheric boundary layer ABL the dense, thin layer of the atmosphere nearest to the Earth-- is dominated by vigorous turbulent mixing produced by aerodynamic drag shear and thermal forcing buoyancy. The depth of the ABL, H, varies with the diurnal cycle, where radiative surface heating during daytime hours acts in conjunction with ambient shear to thicken the ABL, while during nighttime hours the relatively cool surface reverses the affect of buoyancy and suppresses the production of turbulence via shear. The relative contribution to turbulence production via shear and buoyancy is commonly quantified via the Obukhov length. In the absence of buoyancy neutral conditions, turbulence is produced only via shear. For conceptual purposes, the neutrally-stratified ABL may be divided vertically into two horizontal layers the surface and inertial layer, where the former occupies the lowest x19 10 of the ABL and is heavily influenced by attributes of the underlying landscape, while the latter is presumed to be horizontally homogeneous for a balanced ABL 1 and is affected by Coriolis accelerations.

Descriptors:

Subject Categories:

• Fluid Mechanics
• Numerical Mathematics

Distribution Statement:

[A, Approved For Public Release]