Exploring the impact of surface waves on wakes using LES in the WRF model

Despite the high interest in offshore wind harvesting and the numerous studies with regard to internal and external wakes from offshore wind farm clusters, there is surprisingly little knowledge about the impact that waves might have on the performance of wind turbines and the behaviour of their wakes. Here, and for the first time in the Weather Research and Forecasting (WRF) model, we explore the impact of a moving surface wave on the wake of a wind turbine. By studying an intermediate wave case where the flow does not behave as a typical flow over a hill case, we observe the lowest velocities at the wave crests. Turbulence is enhanced over the wave’s steepest slopes. The wake seems to periodically move with the wave, and turbulence is inhibited around hub height downstream of the wake for the cases when waves are present. Our study provides new insights into how wave dynamics affect both the atmosphere and the behaviour of a turbine wake.