Numerical study of hydrodynamic forces and dynamic response for barge type floating platform by computational fluid dynamics and engineering model

The hydrodynamic coefficients are evaluated by fully nonlinear Navier-Stokes forced oscillation simulations using the volume of fluid method. Richardson extrapolation is employed to obtain the grid-independent solution. The predicted hydrodynamic coefficients are validated by the water tank tests. The applicability of the drag coefficient models as the function of Keulegan-Carpenter numbers in the surge and heave directions are investigated for the barge-type floater by comparing with the numerically predicted drag coefficients. The dynamic response analyses are then conducted using the engineering model with the validated drag coefficient models. The predicted mean values of surge and mooring tension without considering drag forces underestimate the measurements in the high wave height condition, where those with considering drag forces show good agreement, which is analytically explained by the mean drag force being inversely proportional to the square of wave period and proportional to the cube of wave height. Dynamic responses of floater predicted without considering drag forces caused overestimation at the natural frequencies in the heave and pitch directions, while those considering drag forces show good agreement with the measurements.