Numerical Simulation of 2D Dam Break Wave on Erodible Sediment Bed

In this paper a 2D model for the simulation of dam break events over a movable bed is presented. Based on a shallow water approach the model assumes the hypothesis of a watersediment mixture throughout (one-layer flow model) and takes into account non equilibrium transport of the sediments by means of an auxiliary relationship that introduces an erosion / deposition velocity. The governing equations are solved in coupled way by the implementation of an explicit first-order finite volume method. The application of the 1D version of the model to some experimental tests did not seem to differ significantly from other more complex models (Costabile & Macchione 2006). The main purpose of this work, therefore, is to analyze the performance of the 2D version of the model proposed by Costabile & Macchione (2006) in more complex geomorphic situations; in particular this study aims to find out whether the bed evolution law continues to work well when referred to a typical 2D behaviour of the dam break waves. Two applications are shown in the paper: the first one refers to a preliminary analysis of the performance of the 2D approach with reference to a dam break test case over erodible bed in a prismatic channel with rectangular cross section (Spinewine & Zech 2002); the second one refers to an experimental test carried out in a rectangular channel with an abrupt enlargement (Spinewine 2005). The numerical results shown in the paper provide encouraging results.