3D numerical simulation of deposition patterns due to sand disposal in flowing water

A 3D numerical model has been developed to study the deposition patterns for sediment dumping in ambient water with cross-flow. The model formulation is based on the governing equations for the conservation of mass, momentum, and density excess, assuming the discrete particles can be represented by a continuous field of density difference with a specified settling velocity. To model the turbulence generated by the particles, a buoyancy extended k-ε model is employed. Numerically, the governing equations are split into three parts in the finite-difference solution: advection, dispersion, and pressure propagation. The advection part is solved by a characteristics-based scheme, the dispersion part is solved by the central difference method, and the pressure propagation part is solved implicity by using the Gauss-Seidel iteration method. The computed results show that two different deposition patterns exist. One is oblong, and the other is horseshoe-shaped, depending on the ratio of the initial negative buoyancy flux of the sand discharge and the horizontal momentum flux of the flow. The computed results are in satisfactory agreement with experiments. The existence of the two different deposition patterns is explained by using the concept of bifurcation of buoyant plumes.