Development of a two-phase SPH model for sediment laden flows

• Published in: Computer physics communications Vol. 221; pp. 259 - 272
• Main Authors: Shi, Huabin, Yu, Xiping, Dalrymple, Robert A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2017
• Subjects: Free surface flow; Sand dumping; Sediment motion; Two-phase SPH model; Sand dumping; Free surface flow; Sediment motion; Two-phase SPH model
• ISSN: 0010-4655; 1879-2944
• DOI: 10.1016/j.cpc.2017.08.024

A SPH model based on a general formulation for solid–fluid two-phase flows is proposed for suspended sediment motion in free surface flows. The water and the sediment are treated as two miscible fluids, and the multi-fluid system is discretized by a single set of SPH particles, which move with the water velocity and carry properties of the two phases. Large eddy simulation (LES) is introduced to deal with the turbulence effect, and the widely used Smagorinsky model is modified to take into account the influence of sediment particles on the turbulence. The drag force is accurately formulated by including the hindered settling effect. In the model, the water is assumed to be weakly compressible while the sediment is incompressible, and a new equation of state is proposed for the pressure in the sediment–water mixture. Dynamic boundary condition is employed to treat wall boundaries, and a new strategy of Shepard filtering is adopted to damp the pressure oscillation. The developed two-phase SPH model is validated by comparing the numerical results with analytical solutions for idealized cases of still water containing both neutrally buoyant and naturally settling sand and for plane Poiseuille flows carrying neutrally buoyant particles, and is then applied to sand dumping from a line source into a water tank, where the sand cloud settles with a response of the free water surface. It is shown that the numerical results are in good agreement with the experimental data as well as the empirical formulas. The characteristics of the settling sand cloud, the pressure field, and the flow vortices are studied. The motion of the free water surface is also discussed. The proposed two-phase SPH model is proven to be effective for numerical simulation of sand dumping into waters.