Abstract
A model for the simulation of wind flow in complex terrain is presented based on the Reynolds averaged Navier–Stokes (RANS) equations. For the description of turbulence, the standard k-ε, the renormalization group (RNG) k-ε, and a Reynolds stress turbulence model are applied. Additional terms are implemented in the momentum equations to describe stratification of the Earth’s atmosphere and to account for the Coriolis forces driven by the Earth’s rotation, as well as for the drag force due to forested canopy. Furthermore, turbulence production and dissipation terms are added to the turbulence equations for the two-equation, as well as for the Reynolds stress models, in order to capture different types of land use. The approaches for the turbulence models are verified by means of a homogeneous canopy test case with flat terrain and constant forest height. The validation of the models is performed by investigating the WindForS wind test site. The simulation results are compared with five-hole probe velocity measurements using multipurpose airborne sensor carrier (MASC) systems (unmanned small research aircraft)—UAV at different locations for the main wind regime. Additionally, Reynolds stresses measured with sonic anemometers at a meteorological wind mast at different heights are compared with simulation results using the Reynolds stress turbulence model.
Highlights
Most of the wind turbines in Germany are located on flat terrain or in coastal regions
An application of these kinds of Reynolds stress model (RSM) capturing canopy effects for the micro-siting in complex terrain is not known to the authors, indicating that there is a strong need for validation
We describe a way to carry out flow modelling in complex, forested terrain that is accurate and fast enough for micro-siting and for planning of measurement campaigns
Summary
Most of the wind turbines in Germany are located on flat terrain or in coastal regions. Two-equation turbulence models mostly in combination with wall models, for example, standard k-ε or RNG k-ε models, offer great numerical stability combined with a relatively low demand on computational resources Their application for the computation of wind flow in complex terrain with strong velocity gradients has shown to give acceptable results despite the assumption of an isotropic turbulence [5,6,7]. Dimitris and Panayotis [18] compared the simulation results with measurements from laboratory channels with aquatic vegetation An application of these kinds of RSM capturing canopy effects for the micro-siting in complex terrain is not known to the authors, indicating that there is a strong need for validation. The validation of the models is carried out by means of an unmanned aerial vehicle (UAV) and 3D-ultrasonic anemometer measurement data for the WindForS test site
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