Simulation of Coupled Analysis for Crane Ship and Suspended Load in Waves

This paper presents a CFD analysis method to evaluate the behavior of a ship in regular waves, assuming that the floating load is a pendulum. Evaluating the behavior of a ship in waves is very important from the point of view of safety and availability; in the CFD analysis, the overset grid method, which superimposes multiple meshes, is used to reproduce the motion of the ship. Periodic external forces are applied to the jib points to account for the effects of suspended load motion. The coupled motions of a hull and a lifting barge were calculated using the MBD (Multibody Dynamics) calculation method. The objective of this study is to develop a coupled motion simulation method that integrates an MBD solver and a computational fluid dynamics (CFD) solver. Hydraulic experiments were also conducted to verify the accuracy of the analysis and to develop a two-way weak coupled analysis method to solve the time evolution of the hull and lifting motion in a wave field. The results show that the ship’s behavior slightly changed when the natural frequency of the suspended load was brought closer to that of the waves. It is also shown that the mass ratio of the load and the ship can be an important parameter. Although the model was able to capture the motion tendencies of the hull and suspended load, it was not able to accurately simulate the observed actual phenomena.