The influence of wave steepness and age on wake dynamics and power performance of offshore wind farms

Offshore wind energy, valued for its wide distribution, high wind speed, and low turbulent disturbance, is experiencing rapid growth. Air–sea surface waves pose new challenges in managing offshore wind resources through additional wind–wave interactions in the marine boundary layer system. This study uses large eddy simulation to investigate wave-induced effects on airflow and wake turbulence around wind turbines and assess the corresponding effects on the power output of an offshore wind farm. Particularly, the numerical experiment is designed to explore how wake dynamics and wind power are modulated by the wave steepness and age. A moving surface drag model is employed to account for wave-induced drag on airflow. Results indicate that waves significantly influence wind profiles and stress within these farms. Increased wave steepness elevates overall drag, reducing wake recovery and power output; while more developed waves enhance sea-to-air momentum flux and turbulence intensity, accelerating wake recovery and boosting power output. Specifically, offshore wind farm power output shifts from sub-linear to super-linear growth as wave transition from the wind-driven wave regime to the wave-driven wind regime. These findings suggest new engineering opportunities for optimizing offshore wind farm performance based on local wave climatology.