Dynamic response analysis of a fully coupled aerodynamic-hydrodynamic-mooring-anchor floating offshore wind turbine

Floating offshore wind turbine (FOWT) is restrained by the mooring system, and the motion response of FOWT leads to complex interaction among the anchor, chain, and soil. The conventional aerodynamic-hydrodynamic-mooring model of FOWT typically assumes a fixed boundary constraint at the seabed for the mooring system, neglecting the interaction of anchor-chain-soil. The assumption affects the global responses of FWOT. This paper establishes a finite element model for the dynamic interaction of the anchor-chain-soil system based on the Coupled Eulerian-Lagrangian (CEL) method in Abaqus, introducing a method to approximate the interaction through equivalent stiffness and damping. Then, through joint simulation with OpenFast and Orcaflex, a fully coupled aerodynamic-hydrodynamic-mooring-anchor model of FOWT is developed to study the impact of the anchor foundation on the dynamic characteristic of FOWT. Compared with the new proposed aerodynamic-hydrodynamic-mooring-anchor model, it is found that the traditional model underestimates the maximum horizontal response of platform and overestimates the mooring line tension.