Numerical investigation of coupled responses of a mining vessel and moonpool in regular and irregular waves with varying moonpool aspect ratios using SPH

Abstract

The moonpool parameters of deep-sea mining vessels impact their hydrodynamic performance significantly. However, there has been limited research on coupled dynamic response characteristics of vessels with varying moonpool aspect ratios under different wave environments, particularly the influence mechanisms of nonlinear fluid dynamics within the moonpool. This study investigates the impact of incident waves under different environments on the motion responses of the moonpool-mining vessel coupled system. The SPH method is used to explore the interaction between surface waves and the vessel. The accuracy of the computational algorithm in generating incident waves has been verified through comparison with laboratory experiments. Additionally, the impact of incident waves on the motion responses of dynamically positioned mining vessels is considered by adjusting the moonpool aspect ratio. The focus is on the nonlinear characteristics induced by fluid resonance within the moonpool and the impact of higher harmonics, generated by the fundamental wave, on the vessel's motion amplitude. The findings demonstrate that the amplitude of the vessel's heave motion is positively correlated with the main frequency peak of the fluid in the moonpool. The high-order harmonic phenomenon excited by the fundamental wave in the moonpool cavity is significantly obvious for the rolling motion response curve.