Numerical simulation of sand bar in downstream of back step structure with sudden expansion

Abstract

In this paper, the numerical simulations of flow and bed deformation under the experimental conditions are carried out to verify the applicability of numerical models and to clarify the mechanism of the sandbar formation at the downstream of the back-step. In order to simulate the bed deformation, two conditions common equilibrium sediment transport model and the non-equilibrium model for bed-load transport are tested. It is shown that the result of non-equilibrium sediment transport model is in good agreement with the experimental results, in which sediments were deposited in the middle of the channel and along the sides where shockwaves are generated. However equilibrium sediment transport model was not able to capture the well features of sandbar formation. Furthermore, we clarified the mechanism of sandbar formation at the downstream of back-step by the results of non-equilibrium model.