A Semi-Coupled Model for Morphological Flow Simulation in River Bend

Abstract

This paper presents a new efficient and robust numerical model for morphological flow simulation in river bends. The hydrodynamic model is developed by solving the two dimensional (2D) shallow water equations using a total variation diminishing (TVD) MacCormack predictor corrector scheme. The present TVD method is very simple and provides accurate results free from numerical oscillations near sharp gradient. The effective stresses are modeled by using a constant eddy viscosity model. The sediment transport model solves the Exner equation using a simple forward time and central space (FTCS) finite difference algorithm. The sediment transport model incorporates the helical flow and the transverse bed slope effects on the sediment direction computation. These models are coupled using the semicoupled approach. The present semicoupled model is used to replicate two popular experimental test cases of both tight and loose channel bends. The obtained results in terms of bed level variation reveal that the model can accurately simulate several features of the bed changes such as oscillations of the transverse bed profile with the formation of point bars and pools along the banks. The values obtained for three widely used statistical parameters show the applicability of the present model for this type of complex scenarios.

Keywords

• shallow water equations; exner equation; tvd maccormack scheme; ftcs scheme; semi-coupled model; sediment transport model.