Effect of swell-induced pitching motion on power production and wake dynamics of a floating offshore wind turbine at various wave ages

Wake dynamics and power output of floating offshore wind turbines (FOWTs) are highly influenced by sea state. The present study focuses on revealing the combined effects of downwind swell and FOWT pitching motion on power production, wake evolution, and coherent vortex structures over representative wave ages (Formula presented) and pitching amplitudes ((Formula presented) ). Large-eddy simulations of turbulent flows over downwind propagating swells are conducted, parameterizing the turbine rotor with an actuator line model. For non-pitching turbines ((Formula presented) ), downwind swells increase the mean power output (Formula presented) by about 44 % and 60 % at wave ages (Formula presented), respectively, while the increase is negligible at (Formula presented). When the platform pitching motion is included, the enhancement in P_outis most pronounced at (Formula presented), exceeding those observed at lower wave ages. Swell-induced platform pitching motion also accelerates wake momentum recovery due to high turbulent kinetic energy generated in the near wake. As the pitching amplitude increases, the wake recovery improves because of enhanced turbulent mixing and earlier hub–tip vortex interactions.