2D Numerical model for river flow and bed evolution based on unstructured mesh

Abstract

This paper describes a 2D (Two-dimensional) numerical model, through which the flow field and bed evolution in alluvial channels can be simulated The model is formulated on an unstructured mesh using FVM (Finite volume method) and allows employment of hybrid polygons. This model calculates the velocity field by solving the unsteady shallow water equations with the widely used k-ε model for the turbulence closure. The bed evolution is simulated through the sediment continuity equation with an empirical formula for the bedload transport rate. The secondary flow effects on both the mean flow and the near-bed flow are considered The model has been applied to predict the flow and bed evolution in a large-scale physical model experiment in a river restoration project. It is shown that the simulation result has a reasonable accuracy.