Developing a multi-region coupled analysis method for floating offshore wind turbine based on OpenFOAM

As floating offshore wind turbines (FOWTs) continue to scale up in size, the simulation technology for coupling aerodynamic, hydrodynamic, and mooring forces presents significant challenges. This study proposes a multi-region coupled simulation solver, MRFoam, for FOWTs. The multi-region coupled method divides the computational domain into two parts: the turbine region and the floating platform region. This division reduces the number of grid cells and facilitates modular simulations for various structural forms and operating conditions. Compared to the traditional fully coupled method, the multi-region coupled method significantly improves computational efficiency. For various models and grid quantities, the computational efficiency of the multi-region coupled method is nearly double that of the fully coupled method with the results remaining almost identical. Subsequently, the multi-region coupled model is applied for the aerodynamic, hydrodynamic and mooring dynamic analyses of a large-scale FOWT (IEA 15 MW) under various wind and wave conditions. The study found that a decrease in wind speed increases the amplitude of surge response while decreasing the amplitude of heave response. Additionally, at lower wind speeds, an increase in wave height amplifies the platform's motion response, while the variation in aerodynamic thrust is slightly influenced by the change in the platform's motion amplitude.