32. CFD-Type Wake Models

CFD-type wake models are widely used to investigate the physics of the flow through wind turbines and wind farms, in particular with regard to the interaction between the atmospheric boundary layer and wind turbine wakes. This distinguishes them from engineering-type wake models that are preferred in industrial applications which need simple and fast results. The first part of this review focuses on the theory of CFD-type wake modeling. The three most widely used CFD-type wake models are described in detail: The standard uniformly loaded actuator disk model, an advanced actuator disk model including distributed forces and rotational effects and the actuator line model. A few other actuator models will be covered briefly. Furthermore, methods to model the effect of tower and nacelle are reviewed as well as the implementation of control mechanisms as speed, yaw and pitch control. Sections on tip-loss corrections, the inclusion of blade generated turbulence and the process of smearing the forces on the computational grid complete the first part. The second part of this review focuses on applications of CFD-type wake models, starting with an overview over verification and validation studies. Next, various application fields are reviewed, grouped by topic, with emphasis placed on the impact of atmospheric stability and terrain.