Validation of CFD-Based Numerical Wave Basin for a Floating Offshore Wind Turbine in Irregular Waves and Dynamic Wind

Abstract

Abstract Several recent benchmark studies have demonstrated that Computational Fluid Dynamics (CFD) is capable of capturing both nonlinear and viscous effects in marine hydrodynamics and predicts wave- and current-induced offshore platform motions accurately. A CFD-based numerical wave basin developed by Technip Energies, MrNWB [1, 2], has been well-validated against physical model test results for various offshore floating platforms including a floating offshore wind turbine in National Renewable Energy Lab (NREL)’s OC6 CFD JIP [3]. However, the OC6 CFD JIP focused on the motion responses corresponding to hydrodynamic loadings only. In the present study, a new coupled analysis methodology is introduced to accurately predict the motion responses of a floating offshore wind turbine considering wind turbine. In the present coupled analysis, aero-servo-elastic behaviors of the wind turbine blade and tower are simulated by OpenFAST [4], and the hydrodynamic loads on the floating platform and mooring system are simulated by Technip Energies’ CFD-based numerical wave basin tool, MrNWB. For the fully coupled aero-hydro-servo-elastic simulation, the OpenFAST dynamic solver calculates the system responses of floating offshore wind turbine, and the hydrodynamic loads on the floating substructure are integrated into the CFD solver with respect to the 6-DOF platform motions. This new coupled analysis tool is called Wind Turbine Numerical Wave Basin (WTNWB). This paper presents validation of WTNWB for the DeepCWind semisubmersible model tests in irregular waves and a steady wind condition. The validation results are systematically compared with model test results [5, 6] and show good agreement.