Dynamics analysis of deep-sea mining pipeline system considering both internal and external flow

The transportation pipeline subsystem is an essential part of the deep-sea mining system. In order to explore the internal flow field of the pipeline, the internal flow simulation is carried out by CFD-DEM coupling method. The pressure and wall shear stress of the pipe are computed to show the influence of internal flow on the pipelines. Moreover, a novel multi-body dynamic model of the pipeline system is established by the lumped-mass finite element method (LM_FEM) considering both internal and external flow to investigate its dynamic performance. The model includes a 900 m lifting rigid pipe, a 400 m conveying flexible hose and a simplified buffer. The results show that the dynamic performance of pipeline system is greatly affected by ocean current angle, sea depth and buoyancy module distribution. As the ocean current angle increases, the maximum bending moment of rigid pipe is significantly reduced, and the value of flexible hose is gradually increased. This study provides an important theoretical basis and technical references for the pipeline design, performance evaluation and coordinated motion control of the practical deep-sea mining system.