A wall-modeled approach accounting for wave stress in Large Eddy Simulations of offshore wind farms

In the context of offshore wind farms, accurate predictions of surface fluxes in the marine atmospheric boundary layer are critical for Large Eddy Simulations (LES) of airflow over waves. The effect of the waves on the airflow is often modeled by prescribing the roughness length in the framework of Monin-Obukhov similarity theory. However, such approaches lack generalizability over different wave conditions due to reliance on model coefficients tuned to specific datasets. Wave phase-resolving simulations on the other hand have higher accuracy but also a higher computational cost. In this work, a sea surface-based hydrodynamic drag model is applied to model the pressure-based surface drag felt by the wind due to the waves. An offshore wind farm configuration is simulated using a wall-modeled LES, with the effect of the waves represented using the wave-drag model and the wind turbines represented by an actuator disk model. The approach is validated with data from high fidelity wave-resolving Large Eddy Simulations. The effect of the waves and the farm configuration on the mean velocity profiles power production, and kinetic energy budget are quantified.