Numerical investigation of nonlinear diffraction wave loads on a suspended cylinder

Abstract

Floating offshore wind turbines (FOWTs) interact with waves in complex sea conditions, inparticular wave-induced nonlinear diffraction wave loads can excite the resonant response of FOWTs in the low frequency range. In this paper, a fixed rigid suspended cylinder (considereda simplification of the support columns of a complex structure) is analyzed for nonlinear waveloads under regular waves using OpenFOAM, an open-source Computational fluid dynamics(CFD) software, to obtain nonlinear hydrodynamic load characteristics of a simple structurein regular waves. Results are compared with experimental and potential flow analysis with theCFD model yielding better estimates of first, second and third order wave diffraction loads than the engineering model using potential flow theory. Engineering models based on second-order potential flow theory are not effective in predicting the second and third order wave
 diffraction loads.