The interaction of wind turbines (WT) and atmospheric flow is investigated not only in field and wind tunnel experiments but also, in particular, with the aid of numerical simulations. Since WTs are almost always operated in a part of the atmosphere where the flow is turbulent and WTs increase the turbulence, it is recommended to use turbulence-resolving models for the most precise calculations of wind farm flows.
A modelling with complete resolution of the atmospheric turbulence (DNS - Direct Numerical Simulation), which would require model area sizes in the kilometre range and grid widths in the millimetre range, is unfortunately not yet possible due to limited computing resources. Currently, the tool of the Large-Eddy-Simulation (LES), which explicitly resolves the large scales of turbulence and parameterizes the effect of the small scales on the large scales, is the most promising tool for the numerical investigation of turbulent flows. Corresponding simulations have a temporal resolution in the sub-second range and a spatial resolution in the range of a few meters.
In ForWind's energy meteorology working group, the LES model PALM developed at the University of Hannover is used. This model is characterized by an extremely effective parallelization and thus high scalability. On the high performance computer system EDDY, which is available to ForWind, the energy meteorology group can thus also investigate the flow conditions in front of and within large wind farms using the LES method.