Numerical Simulation of a Floating Offshore Wind Turbine in Wind and Waves Based on a Coupled CFD–FEA Approach

Abstract

A floating offshore wind turbine (FOWT) normally suffers from complex external load conditions. It is vital to accurately estimate these loads and the subsequent structural motion and deformation responses for the safety design of the FOWT throughout its service lifetime. To this end, a coupled computational fluid dynamics (CFD) and finite element analysis (FEA) approach is proposed, which is named the CFD–FEA coupled approach. For the CFD approach, the volume of fluid (VOF), the dynamic fluid–body interaction (DFBI), and overset with sliding meshes are used to capture the interface of the air and the water and to calculate wind/wave loads and the motion response of the FOWT. For the FEA approach, the explicit nonlinear dynamic finite element method is employed to evaluate structural deformation. The one-way coupling scheme is used to transfer the data from the CFD approach to the FEA approach. Using the NREL 5 MW FOWT with a catenary mooring system as the research object, a series of full-scale simulations with various wind speeds, wave heights, and wave directions are implemented. The simulation results provide a good insight into the effect of aero-hydrodynamics and fluid hydrodynamics loads on both the motion and deformation responses of the FOWT, which would contribute to improving its design.

Keywords

• floating offshore wind turbine
• computational fluid dynamics
• finite element analysis
• aero-hydrodynamic loads
• motion and deformation responses