A Linear 3D Spectral Element Time-Domain Solution to a Floating Offshore Wind Turbine

For many decades linear impulsive formulations have been studied and used to model the interactions between floating offshore structures and waves. The basic principle of these types of formulations is to force the floating body with a velocity impulse and study the resulting force on the body based on potential flow theory. In a recent work done by Visbech et al. (2022), a new 2D model is presented, where the governing equations are discretized using a higher-order Galerkin-based spectral element method (SEM). This numerical method has been established as a basis for modeling wave propagation and wavestructure interactions with complex geometries in an efficient and accurate manner. In conjunction with ISOPE2023, the 1st FOWT Comparative Study will take place. The subject of this study is the hydrodynamic response of a floating offshore wind turbine. The comparison study features a static equilibrium test (with and without mooring forces), a free decay test, and a dynamic wave focus test. The results of our contribution are two-folded: First, we present our numerical analysis (added mass and damping coefficients) using our novel 3D SEM-based solver of the linear radiation problem as a natural higher-dimensional extension of [1]. This model will make use of curvilinear hybrid unstructured meshes to simulate simple - proof of concept - geometries, such as a floating sphere or/and a box. Then secondly, we present our results for the aforementioned comparison study by using the purposed model in combination with pre-developed mooring tool.