Wave-current-wind interaction with elastic floating offshore wind turbines

This study is concerned with rigid-body responses and elastic motion offloating offshore wind turbines (FOWTs) under combined wave, current and wind loads. A numerical approach is developed in frequency domain based on the linear diffraction theory with a Green function for small current speeds and the blade-element momentum method for hydrodynamic and aerodynamic analysis, respectively. This approach is coupled with the finite element method to obtain the hydro- and aeroelastic motion of FOWTs. The interaction of combined wave-current-wind with three FOWTs, namely SPAR, semisubmersible and barge, is considered. Rigid-body responses of the three FOWTs to waves and wind are compared to those when current loads are present. Furthermore, the effect of current speed and misalignment of incident waves with current-wind on the motion of the FOWTs is investigated. Discussion is provided on the importance of considering wave current interaction together with aerodynamic loads on the responses of the considered FOWTs. It is observed that the motion of the SPAR FOWT to combined waves and wind changes the most when the current loads are added. Finally, the effect of wave-current-wind interaction on the elastic motion of flexible FOWTs is investigated and compared with their rigid-body counterparts.