Model comparison of two different non-hydrostatic formulations for the Navier-Stokes equations simulating wind flow in complex terrain

Abstract

An anelastic model and a quasi-compressible model for the simulation of wind flow in complex terrain are presented. The models are based on the Reynolds Averaged Navier-Stokes (RANS) equations in combination with the k-ε turbulence model. Additional terms are implemented in the transport equations to describe stratification of the atmosphere to account for the Coriolis forces driven by the Earth's rotation, as well as for the drag-forces and turbulence production and dissipation due to different types of land use.The modelling approaches are verified by means of academic test cases assessing effects of the Earth's rotation, density driven flow and canopy. The validation of the models is performed by investigating a wind test site near Geislingen a. d. Steige in Southern Germany. Fife hole probe velocity measurements using MASC systems (unmanned small research aircraft UAV) at different locations are compared with the simulation results for the main wind regime. Therefore, the orography and flora of the Earth's surface are described by high-resolution digital data from State Authorities for Spatial Information and Rural Development Baden-Württemberg (LGL). Boundary and initial conditions are based on mesoscale simulation data from the COSMO-DE weather model of the German Meteorological Service (DWD).