2D Modeling of Flow and Sediment Interaction: Sediment Mixtures

Abstract

The further development and application of the two-dimensional (2D) flow and sediment-modeling concept, formulated for the treatment of sediment mixtures, is addressed herein. The sediment domain is divided into subdomains for suspended, active-layer, and subsurface-strata sediments. Governing sediment equations are defined for each subdomain, including sediment exchange mechanisms between suspended sediment and active-layer sediment, as well as active-layer and subsurface sediment. The sediment mixture is represented through a suitable number of sediment size classes, and governing-equations’ terms are defined as size class–specific. Governing equations and associated numerical solutions are formulated within the general nonorthogonal curvilinear coordinate framework. A numerical solution is based on the fractional-step approach, using the characteristics method with higher-order interpolations for both flow and suspended-sediment advection steps. The numerical solution for equations describing active-layer and subsurface sediment is fully coupled, providing that the sum of all sediment size fractions is always equal to unity. Numerical results are compared with the results of field data measurements. The comparison strongly supports the inclusion of sediment mixtures in flow-sediment modeling.