Experimental and Numerical Studies on Ship Motion Responses Coupled with Sloshing in Waves

Abstract

This study considers the motion responses of floating bodies in waves coupled with sloshing-induced internal forces and their effects on sloshing-induced impact loads. The linear ship motion is solved using an impulse-response-function (IRF) method, while the nonlinear sloshing flow is simulated using a finite difference method. The considered models are a liquid natural gas floating production, storage, and offloading unit (LNG FPSO) with two partially filled tanks and a modified S175 hull with an antirolling tank. In the case of the LNG FPSO model, both numerical and experimental studies are carried out. Three degree-of-freedom motion responses are allowed in the presence of regular waves, and the measured response amplitude operators (RAOs) are compared with computational results. For the modified S175 hull, the computational results are compared with other existing computational results. It is observed that the present method provides a fair agreement with experimental and other numerical results, showing significant coupling effects on both motion responses and sloshing flows. The numerical study extends to the observation of pressure field inside the tanks, and a significant difference in internal pressure is also shown.