2DH Computation of Transient Sea Bed Evolutions

A subgrid based approach for morphodynamic modelling

“…In these models the bed load transport vector is used to determine the upwind direction. Characteristic theory can also show that perturbations in the bed can travel in all directions, even in the opposite direction to the sediment transport direction [19]. This can occur when the sediment transport is described as a non-linear function of the flow velocity.…”

“…The strong non-linear coupling between flow and morphological response makes it difficult to deal with these instabilities. Typically, a bed slope effect or a diffusion term is added to the system for stabilization [19]. Alternatively, the stability of simulations can be enhanced by various methods such as a numerical filter [20], a predictorcorrector method and a diffusion term in the Exner equation and combinations of those [21].…”

Model for the Formation and Evolution of Sand Ridges on the Continental Shelf

“…The equation of continuity for the sediment concentration is the advection-diffusion 35) where vf is the sediment "fall velocity"and n = (z + h(X, y, T))/6b1. Assume that, appart from random fluctuations, u and p do not vary much over small transverse spatial scales so that the second term of the above equation may be neglected.…”