Validation of a Generalized Actuator Disk Model in the Weather and Forecasting Model Using Wake Observations from Turbine Wake Inflow Characterization Study

Accurate modeling of inflow conditions and turbine wake effects is essential for simulation of turbine blade loads. The Weather Research and Forecasting (WRF) model, a community developed, public-domain, numerical weather prediction system designed to serve both operational forecasting and atmospheric research needs, can support such simulations. WRF includes a large-eddy simulation (LES) capability for high-resolution simulations of processes in atmospheric boundary layers down to grid sizes of the order of one meter. Recently, a generalized actuator disk representation of turbine wake effects was implemented into the WRF model. We carry out verification and validation of WRF-LES with a generalized actuator disk model of wind turbines by conducting and evaluating simulations against observed wake characteristics taken from the Turbine Wake Inflow Characterization Study (TWICS) dataset. TWICS field study took place in April and May 2011 at the National Renewable Energy Lab's (NREL) National Wind Technology Center (NWTC). TWICS data set includes measurements obtained using meteorological towers and remote sensing systems. These measurements provide a three dimensional spatio-temporal information about the structure and evolution of the inflow to and wake from a modern 2.3 MW turbine with a 100 meter rotor diameter and are therefore suitable for validation of high-resolution LES of a turbine wake.