This paper presents a numerical investigation of a floating offshore wind turbine (FOWT) in a complex marine environment consisting of winds and waves. The investigation takes account of the aerodynamics and hydrodynamics of the FOWT system and their interactions simultaneously by using the hybrid model qaleFOAM, which combines a fully nonlinear potential solver with a two-phase Navier-Stokes solver using a domain decomposition approach. The qaleFOAM model is validated by comparing its predictions with experimental and numerical results available in the public domain and then is applied to model the FOWT in a unidirectional focused wave with a peak period of 42.31 s accompanied by a uniform wind of 11.4 m/s. The result reveals a significant interaction between the aerodynamic and hydrodynamic responses of the FOWT in such conditions. Moreover, it demonstrates that the most extreme response of the FOWT may not occur at the highest wave.
In recent years, the focuses of the research and deployment of the wind turbine have shifted from onshore to offshore sites, from fixed to floating foundations. For the reliability and survivability of a floating offshore wind turbine (FOWT) in complex environmental conditions (winds, waves, and currents), it is critical to accurately predict the response and the performance of the FOWT, which consists of multiple physical processes (e.g., the aerodynamics of the turbine blades, the hydrodynamics associated with the floating foundation, the mooring dynamics, and the control system) and their interactions. Generally speaking, FOWTs are designed to be deployed at offshore sites with high wind resources, which are often accompanied by occurrence of extreme waves. Therefore, considerable nonlinearities and significant interactions are expected in these processes.