The two-phase flow composed of polymetallic nodules and the fluid in hydraulic hoist for deep sea mining was simulated by the discrete particle method (DPM). The motion of nodule particles was simulated by the particle-motion-resolved model, in which the effects of Saffman lift force and Magnus lift force were included. The collisions between particles as well as between particles and the pipe wall were also simulated. The simulated results show some motion characteristics of nodules in hydraulic hoist. These results agree with the experimental results in general.


One of the key techniques in deep sea mining is hydraulic hoist of polymetallic nodules. And the essential for hydraulic hoist is the characteristic of the particle-fluid two-phase flow in the pipe. Wasp (1980), Fei Xiangjun (1994) etc. had completed a lot of studies about the pipeline transportation of two-phase flow composed of fine particles. Because particles are smaller, their velocities can be considered as equaling to the velocity of the ambient fluid. However, in the experiments for hydraulic hoist by Changsha Research Institute of Mining and Metallurgy (CRIMM), it is found that the velocities of polymetallic nodules are remarkably smaller than the velocity of the ambient fluid in the vertical pipe. (Huang etc., 1995) Other investigators have observed the similar phenomena in experiments and provided the valuable experimental results. (Alajbegovic etc., 1994; Lareo etc., 1997; Sobota etc., 2001) The study becomes complicated as the motion of nodules and the flow must be considered respectively. In addition, studies for all the work conditions by experiments are too expensive to be carried out. The numerical simulation has been a powerful method in the research of the particle-fluid two-phase flow with developments of the computer performance and the computation technique. But the computation will be tremendous as the number of particles increases.

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