Comparative analysis of numerical methods for predicting aerodynamic performance of floating offshore wind turbines in tilted conditions

This study evaluates the aerodynamic performance of a floating offshore wind turbine (FOWT) under tilted conditions using four numerical approaches: Computational Fluid Dynamics (CFD), Actuator Line Method (ALM), Blade Element Momentum (BEM) method, and Free-Vortex Wake (FVW) method. The aim is to assess their accuracy and efficiency in predicting thrust, torque, and wake characteristics under tilt and a range of surge and pitch motions. CFD simulations were systematically verified through grid and time-step sensitivity analyses, and all numerical results were compared against experimental data for validation. The results show that BEM tends to overpredict aerodynamic loads, especially torque fluctuations under pitch motions. FVW improves mean thrust and torque predictions but still overestimates torque fluctuations. ALM is sensitive to tilt angles, leading to decreased accuracy at larger tilts. Aerodynamic loads from all methods exhibit a linear dependence on motion amplitude and frequency. CFD and ALM produce similar wake deficit trends, though ALM consistently underestimates the deficits. This comparative study quantifies the predictive performance of different numerical methods for FOWTs under dynamic and tilted conditions, highlighting their strengths and limitations. The findings provide guidance for selecting appropriate modeling approaches depending on the desired balance between accuracy and computational cost.