Numerical investigation of the hydrodynamic characteristics of the polymetallic nodule miner considering the internal fluid field

The internal fluid of the polymetallic nodule miner (PNM) strongly influences its hydrodynamic characteristics. In this study, the internal fluid field is used to simulate the internal fluid flow. The hydrodynamic characteristics of the PNM in linear motion under different operating modes and in rotational motion are investigated via computational fluid dynamics (CFD). Inverse gradients occur at the convex edges of the PNM, where the boundary layers are separated. Detached vortexes and backflows form in the low pressure and velocity regions at the downstream side of the separations. Hydrodynamic forces increase with velocity and are quadratically correlated with velocity. Surface pressures decrease and skin shear stresses increase with increasing velocity. The flow field of the PNM in linear motion exhibits bilateral symmetry, whereas in rotational motion, it becomes asymmetric. During mining operations, pressure and velocity significantly change in the flowing regions of the internal fluid and hydrodynamic forces on the PNM become larger, which are primarily reflected in the collector. In rotational motion, velocity and pressure on the right are higher, and a lateral drag force acts on the PNM. Hydrodynamic force coefficients remain constant at different velocities when not mining. However, they vary with velocity during mining operations.