The impact of wave–current interaction on the dynamic response of a floating offshore wind turbine: A CFD investigation

Floating offshore wind turbines (FOWTs) are critical for deep-water renewable energy, but their dynamic response under combined wind, wave, and current conditions involves complex, nonlinear interactions that challenge accurate prediction. This study presents a high-fidelity computational fluid dynamics (CFD) model within the OpenFOAM framework, incorporating a new coupled wind–wave–current inlet boundary condition. The integrated numerical approach couples a multiphase flow solver (olaFlow), an actuator line model (ALM) for aerodynamics, a dynamic mooring model (MoorDyn), and a six-degree-of-freedom motion solver. Simulations under both normal and extreme conditions reveal that while the mean surge excitation force follows a linear superposition of individual environmental loads, the resulting mean displacement deviates significantly under large motions due to mooring system nonlinearity. In contrast, wave–current interaction (WCI) profoundly amplifies the wave-frequency surge response, with surge amplitudes increasing up to fourfold under normal conditions and doubling under extreme conditions. This amplification affects the overall platform motions and influences nacelle dynamics. As a result, it induces fluctuations in power output and thrust loading, undermining power generation stability and posing risks to blade safety and platform integrity. The study concludes that fully coupled simulations are essential for realistic FOWT design and assessment.