Need for Advancing the Wave Load Modelling on Monopile Offshore Wind Turbines

This paper is introducing an ongoing doctoral research project on wave load modelling on monopilesupported offshore wind turbines, the state-of-the-art review and motivations behind it. Offshore wind provides a clean and inexhaustible source of energy with fewer noise and visual impact constraints. However, offshore wind technology is still very costly and the support structure accounts for a large part of the expense. Monopiles are the most common support type for offshore wind turbines, and they are prone to highly nonlinear excitations, such as ‘ringing’, when exposed to steep waves. These dangerous nonlinear effects are omitted if linear or weakly nonlinear wave theories are used, which is the case for the majority of current solvers. In addition, Morison’s equation is normally used for hydrodynamic loading calculations in the industrial solvers due to its simplicity, but researchers have expressed doubts for its suitability where nonlinear effects count. The introduced doctoral research project therefore aims to improve current aerohydro-servo-elastic solver without excessively compromising the computational efficiency. Work is conducted on two main areas: a potential flow Boundary Element Method code for fully nonlinear water waves, and a comparison study including Morison’s equation, its corrections and FNV theory to determine most appropriate hydrodynamic loading model.