Hydrodynamic investigation of a large monopile for offshore wind applications: Numerical and experimental approaches

The offshore wind industry is looking at large wind turbines say more than 12 MW. Large-diameter monopile foundations are so far the most promising considering the levelised cost of energy, and the industry has demonstrated the ability to push the fabrication boundaries. Designing of offshore wind turbines for a long life service needs to estimate the environmental loads acting on them as precise as possible. In this research, it is aimed to compare the hydrodynamics using three different approaches to investigate the extreme loads acting on monopiles with different numerical and experimental approaches. Specifically, numerical methods employed include Computational Fluid Dynamics (CFD) and the potential flow theory using Morison’s formula with FAST and FlexCom as a simpler method for the estimation of wave kinematics and loads. The experimental tests are conducted at a scale of 1:50 in a wave tank located in Queen’s University of Belfast (QUB). This approach enables different, powerful and industrially standard numerical modelling tools to be compared with the experimental tests in various sea states in the North Sea. The performance of numerical modelling tools for estimation of the loads are investigated as well as the capability of capturing the nonlinear components of forces and wave kinematics.