Towards the Numerical Modelling of Floating Offshore Renewables

Two finite element models are coupled, with the aim of computing the mutual interactions between fluids and floating solids. The fluid and solid domains are discretised differently in space and time, and at every time step, the solid mesh is mapped onto the fluid mesh. The effect of the solid on the fluid dynamics, and vice versa, is modelled through a volumetric penalty force added to the momentum balances of the fluids and solids. A novel algorithm ensures that the action-reaction principle is satisfied at the discrete level. The coupled models are used to simulate uniform flow past a wind turbine, which is represented as a fixed actuator disc. Preliminary results on a floating pile also demonstrate the applicability of the models to fully coupled simulation of a floating spar. This work is a first-step towards the fully coupled modelling of floating wind turbines.