Study on Nonlinear Hydrodynamic Force on Vertical Motion of a Column Structure with a Heave Plate

In this study, hydraulic experiments were conducted on a semisubmersible floating foundation of an offshore wind turbine. In the experiments, the elemental floating model as a side column cut out of a semisubmersible floating foundation was forced to move up and down with various periods in a basin, and the vertical force acting on the elemental floating model was measured to estimate the drag coefficient Cd, which is considered to be damping due to vortices and viscosity. The results were almost the same as the drag coefficient Cd calculated by the previously proposed and validated formula. In addition, we performed numerical simulations using OpenFOAM to reproduce the hydraulic experiments, and they were compared and the agreements were verified, suggesting the use of CFD as an alternative to hydraulic experiments.