15 Numerical Modelling of Thermally Driven Flows over Simple Slopes and Sensitivity Analysis to Surface and Ambient Conditions

Tuesday, 26 June 2018
New Mexico/Santa Fe Room/Portal (La Fonda on the Plaza)
Claudio Pincin, University of Trento, Trento, Italy; and M. Dumbser and D. Zardi

The thermally driven flow occurring over a simple, indefinitely extended slope is simulated by a numerical model solving momentum, thermal energy and turbulent kinetic energy equations. Following Prandtl (1942) and Schumann (1990), the flow is assumed invariant along the slope, whereas time dependence is allowed as in Defant (1949) and Zardi and Serafin (2015). Various closures for turbulent fluxes are tested and compared, including the first-and-one-half turbulence closure model proposed by Rao & Snodgrass (1979). A sensitivity analysis of the flow to topographic and ambient conditions - such as slope angle, surface roughness, ambient stability and surface forcing – as well as to different closures, is performed. Results are compared with existing datasets from field measurements and other models.


Defant F. 1949. Zur Theorie der Hangwinde, nebst Bemerkungen zur Theorie der Berg- und Talwinde. Arch. Meteor. Geophys. Bioklimatol. A1: 421–450 [English Translation: Whiteman, C.D. and Dreiseitl, E., 1984: Alpine meteorology. Translations of Classic Contributions by A. Wagner, E. Ekhart, and F. Defant. PNL–5141/ASCOT–84–3, Pacific Northwest Laboratory, Richland, Washington, 121pp.].

Prandtl L. 1942: Führer durch die strömungslehre, ch. V. Vieweg und Sohn [English translation: Prandtl, L., 1952: Mountain and valley winds in stratified air, in Essentials of fluid dynamics, Hafner Publishing Company, pp.422-425], pp. 373–375.

Rao, K. S., and H. F. Snodgrass, 1979: Some parameterizations of the nocturnal boundary layer. Boundary-Layer Meteorology, 17, 15–28.

Schumann U., 1990: Large-eddy simulation of the up-slope boundary layer. Quart. J. Roy. Meteor. Soc. 116, 637–670.

Zardi, D. and S. Serafin, 2015. An analytic solution for daily-periodic thermally-driven slope flow. Quart. J. Roy. Meteor. Soc., 141, 1968–1974.

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