Semicoupled and fully coupled numerical models for morphodynamic flow simulation in river with irregular planforms

Abstract

This paper introduces one dimensional (1D) as well as two dimensional (2D) numerical models to simulate the morphodynamic processes in open channel flows. The models use the shallow water equations for hydrodynamics and the Exner sediment continuity equation for bed morphology. The governing equations are solved here using the finite difference method (FDM) based Lax-Wendroff scheme. The 1D model uses the fully coupled approach. The 2D model however solves the boundary fitted governing equations of water flow and sediment transport coupled using the semicoupled approach. The numerical oscillations produced due to second order accuracy of the proposed models are removed here by adopting an efficient Total Variation Diminishing (TVD) technique. The influence of helical flow intensity and lateral bed slope are integrated in the sediment transport model for correctly simulating the morphodynamics in channel bends. The practical applicability of the developed models is evaluated by replicating five benchmark test cases of known analytical and experimental results and promising outcomes are obtained. Three widely used statistical parameters are also calculated to check the robustness of the proposed models.