Decoupling wind-wave-wake interactions in a fixed-bottom offshore wind turbine

In the golden age of renewables, offshore wind-energy holds the most potential for growth, but the benefits are also entangled in dynamics not fully understood, such as the dynamic coupling of the atmospheric boundary layer, the turbine generated wake, and the surface waves. This study establishes the first experimental turbulent-interaction between the traditionally distinct fields of airflow-dynamics above the air-sea interface and turbine wakes.  The experimental setup combined a wave tank, wind tunnel, and scaled fixed-bottom wind turbine. Particle image velocimetry (PIV) was performed to visualize wind-wake, wind-wave, and wave-wake interaction far downstream of the turbine. The wave phase-dependent dynamics of the turbine wake on the passing ocean-wave profile and location are outlined. The data were decomposed into incremental wave-phases revealing localized and predictable velocity maxima, stress maxima, and wake modulation that is normally obscured by a time-averaged mean. The results illustrate a more complete picture of offshore wind-energy dynamics, which have implications for insidious mechanical issues, design optimization and/or control strategies.