Numerical Study of Partial Dam–Break Flow with Arbitrary Dam Gate Location Using VOF Method

Abstract

This paper aims to evaluate the crucial influence of the width of dam gate and its position, as well as initial water depth, on the evolution of rarefaction waves on reservoirs, and of shock waves over dry flood plain areas. The large eddy simulation (LES) model and volume of fluid (VOF) method are used to simulate three objectives. Firstly, validation of the presented numerical model, and of mesh sensitivity analysis, are conducted by means of a physical test case, taken from the literature, showing very good accuracy with a small value of RMSE among all hydraulic features in the case of fine mesh. In this direction, the 3D result is also compared with the published 2D one, to prove the necessity of using a 3D model in performing dam–break flow in an early stage. The second aim is to look for insight into the following 3D hydraulic characteristics of dam–break flow: water depth, velocity hydrograph and streamline, vorticity, the q–criterion incorporated with variety of breach size, initial water stage and the reservoir outlet’s location. The influence of the dam gate’s place on peak discharge is pointed out by means of a 3D model, while the existing analytical solution is not specified. With the same conditions of initial water depth, breach width and geometry, an analytical solution gives the same peak discharge, while a 3D numerical one indicates that a symmetrical dam gate provides a greater value than does the asymmetrical case, and also a value greater than that of an analytical result.

Keywords

• hydraulic characteristics
• LES
• partial dam–break
• dam gate location
• VOF