An accurate solver for 3-D suspended sediment dispersion in tidal flow

Sediment dispersion is modelled using a semi-implicit finite-volume scheme for the diffusion-advection equation. Accurate prediction of the settling of dredged spoil is the main motivation. The simplified hydrodynamics of parallel oscillatory tidal flow are assumed locally employing k - epsilon turbulence modelling with wall functions. The mesh spacing in the vertical direction varies parabolically to give fine resolution near the bed and free surface. In the diffusion-advection equation for concentration c vertical diffusion terms are handled implicitly, horizontal-diffusion explicitly and source terms semi-implicitly or explicitly and advection terms explicitly with upwind interpolation. The latter is a problematic issue and a third-order accurate flux-limited scheme is shown to be effective.