A smoothed particle hydrodynamics (SPH) study of sediment dispersion on the seafloor

Ocean-scale sediment dispersion and sedimentation problems are studied using the Smoothed Particle Hydrodynamics (SPH). A SPH formulation based on a mixture model for two-phase flows is developed to investigate the problem. The sediment mass transport via the settling advection and the turbulent diffusion of the suspended sediment are fully accounted for in the current SPH model. The simulations are carried out in an opened boundary domain with a unidirectional underlined current, with relevant deposition/re-suspension boundary conditions on the seafloor. The factors influencing the sedimentation process, such as the hindering and the bottom shear stress effects, are also considered. The simulation results reveal that the sediment convection near the sediment source location is caused by both the ocean current and secondary density driven flows that are created by the concurrent settling motion of suspended sediment particles, while the downstream sediment transport in the far field is only driven by the ocean current. The peak sediment concentration in the ambient ocean water is found to correlate with the sediment release rate, and the settlement rate is inversely proportional to the initial height of the disturbed sediment.