Jun Li

This study examines the strongly nonlinear cross-media dynamics of a deep-sea umbilical cable–payload system during free-surface crossing under different sea states and lifting speeds. A two-dimensional time-domain lumped-mass model was established, in which the cable was discretized into node–axial elements. Morison-type hydrodynamic loading, added mass, and a continuous air–water parameter transition governed by an immersion factor were included for both the cable and the lower-end payload. To improve numerical robustness in long-duration simulations, a segmented ODE15s integration scheme was adopted, together with a smooth-start lifting–heave boundary condition and an adaptive lift-height correction procedure to ensure a stable cross-media response window. The results show a clear spatially segmented response: the upper cable remains nearly straight, whereas the middle and lower sections accommodate most of the lateral offset and curvature redistribution, which intensify under stronger environmental forcing. Top tension shows a gradually increasing mean component superimposed on quasi-periodic oscillations, while bottom tension, detrended vertical payload displacement, and vertical hydrodynamic force are more sensitive to sea-state severity and lifting speed. These results provide a comparative numerical basis for identifying response trends, screening lifting speed options, and interpreting cross-media load transfer mechanisms. Because the formulation is two-dimensional and has not yet been validated against model-scale or full-scale measurements, the results should not be interpreted as equipment-specific safety limits.

The conveying hose is an important piece of equipment in the field of Marine engineering. Its spatial configuration and force conditions affect the normal operation of the Marine engineering system. This paper proposes a flexible, fully hose-based conveyance method for the field of deep-sea mining and mainly uses Orcaflex software to simulate and analyze the characteristics of the conveying hose in this system. This paper studies the influences of the top spacing, incoming flow direction, and placement and recovery processes on the configuration characteristics and force conditions of the hose. The conclusion drawn is that the conveying hose studied in this paper can maintain a good spatial configuration underwater and has a stable force condition. When the top spacing is 20 m, the transition of the curved section at the bottom of the hose is relatively smooth. The top tension of the hose has a good adaptability to the top spacing and the direction of the incoming flow. The conveying hose can stably complete the deployment and recovery operations.