Numerical prediction of wave excitation forces on a fixed tension leg platform concept for offshore wind turbines

To predict wave excitation forces on a fixed Tension Leg Platform Wind Turbine (TLPWT), two numericalsoftware packages were used, namely the CFD code STAR-CCM+ and ANSYS AQWA. The CFD code solvedthe fully-nonlinear Navier-Stokes equations in a time domain whereas ANSYS AQWA solved the lineardiffraction problem in a frequency domain. In both domains, the horizontal wave excitation forces on a genericTLP structure under several deterministic regular wave conditions of a mild sea state were predicted. The sizeof the mesh/panel was fine-tuned to yield optimum results for both solvers. It was found that the horizontalforces obtained by the linear diffraction solver were larger in magnitude than CFD predictions. The lineardiffraction solver provided an insight into the horizontal force experienced by the TLP structure, and hence itcould be used to verify CFD results. However, as the linear diffraction theory does not account for the effectof turbulence, viscous effects or the effect of the air phase, CFD codes could be used to investigate suchphenomena and provide further details