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

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.

References

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