2D Simulation of Non-Uniform Sediment Transport in a Channel Bend in Unstready Flow

Abstract

The interest in rivers is as old as human civilization itself. The rivers seldom flow in a straight path and usually trace out in curved paths. An alluvial river is having the same bed material as the material it moves along the bed and in suspension. The movement of water is intimately linked to the sediment load that it carries. These morpho-dynamic processes cause the river to change its shape, slope, sediment sorting/, etc. Riverbeds of natural streams are more vulnerable to temporal and spatial changes. These processes are mostly found in river bends as river bends are mostly subjected to sorting processes. There are two objectives of this research, first, we have to check the 2D model (Basic Simulation Environment) capability to reproduce experimental results of channel bend having an angle of 1800 and a constant radius. The second objective is to perform the sensitivity analysis of the 2D model, in which inner particles will inform us about the most sensitive model parameters that decisively influence the results. The research simulates the changes in bed topography in an alluvial channel bend under unsteady flow conditions with non-uniform sediment. Experimental data collected during experimental research having a channel bend of 1800 and a constant radius of curvature was used to validate the numerical results. Five experiments were done on the channel bend in a laboratory having different inflow hydrographs. The numerical results in the bend showed scouring at the outer bank and deposition at the inner bank, which tallied with the observed behavior. The research showed that a 2D model can successfully predict the morpho-dynamic changes in a laboratory channel. The sensitivity analysis is also done in this research which shows the sediment transport formula is the most sensitive parameter in the basement model.