Modelling of Wind Flows over Complex Terrain Using a DES Method
This study focuses on the application of detached eddy simulation (DES) for siting of wind turbines in complex terrain. The DES method uses a SST k-ω model as the Reynolds-averaged Navier-Stokes (RANS) model in the near-wall regions. The model switches to large eddy simulation (LES) mode if the dynamic length scale is greater than the local length scale. Therefore, in flow separation zones where the turbulent kinetic energy is large, the flow field is simulated with LES mode. This method is a standard practice in DES and many commercially available computational fluid dynamics (CFD) codes use it to determine the model behaviours. In contrast to traditional RANS studies, a significant advantage of DES is its capability of resolving a time-dependent flow field. One can observe the transient flow behaviours instead of a stationary mean value. This is useful if we want to understand the scale of fluctuating wind and the unsteadiness of the wind across the rotor area of a wind turbine. Applying this DES method can distinguish flow separation zones in complex terrain and this has been helpful to identify wind problems which may cause difficulties in operation of wind turbines.
KeywordsComputational Fluid Dynamic Wind Turbine Wind Farm Complex Terrain RANS Model
Unable to display preview. Download preview PDF.
- Bechmann, A., Sørensen, N.N., Johansen, J., Vinther, S., Nielsen, B.S., Botha, P.: Hybrid RANS/LES method for high Reynolds Numbers applied to atmospheric flow over complex terrain. Journal of Physics: Conference Series 75, 012054 (2007)Google Scholar
- Brodeur, P., Masson, C.: Numerical simulations of wind distributions over very complex terrain. In: 44th AIAA Aerospace Sciences Meeting and Exhibit, January 9-12 (2006)Google Scholar
- CD-adapco, User Guide, STAR-CCM+ Version 5.06.010, London, UK (2010) Google Scholar
- ESDU, Mean wind speeds over hills and other topography. ESDU data item 91043 (2007)Google Scholar
- Jørgensen, B.H., Ott, S., Sørensen, N.N., Mann, J., Badger, J.: Computational methods in wind power meteorology. Risø-R-1560 (EN) (2007)Google Scholar
- Menter, F.R., Kuntz, M.: Adaptation of Eddy Viscosity Turbulence Models to Unsteady Separated Flows Behind Vehicles. In: The Aerodynamics of Heavy Vehicles: Trucks, Buses and Trains. Springer, Asilomar (2002)Google Scholar
- Spalart, P.R.: Young-Person’s Guide to Detached-Eddy Simulation Grids. NASA-CR-2001-211032 (2001)Google Scholar
- Wright, N.G., Hargreaves, D.M.: Unsteady CFD simulations for natural ventilation. International Journal of Ventilation 5(1), 13–20 (2006)Google Scholar