Kinematic and dynamic analysis of dam break flow impact on vertical walls using weakly compressible SPH

Abstract

This article presents the kinematic and dynamic analysis of a dam break flow based on data obtained from numerical solutions by the smoothed particle hydrodynamics (SPH) method. The method and original algorithms necessary for correct pressure evaluation are thoroughly described. The pressure evaluation method consists of data reading using virtual sensors and filtration in the time domain using the weight function. A simple convergence study showing the independency of the evaluated parameters of spatial resolution is presented together with validation of the introduced methods and algorithms using a simple hydrostatic problem and experimental data available in the literature. We focus on two parameters that describe the problem: distance of the downstream vertical wall from the edge of the liquid column and the column’s height to width ratio. We found that the impact can be divided into three consecutive phases characterized by specific kinematic (flow patterns) and dynamic (exerted pressure and forces) behavior and different roles of the investigated parameters during these phases. During the early stages of an impact, the column’s distance from the vertical wall plays a major role. A dependency between the column distance and the force peak in this stage was identified in the form of a power function. In the second stage, when a rolling wave emerges, the vertical wall position influences the shape of the wave and the pressure distribution on the wall. The total force is greater in this phase for lower column height to width ratios due to the higher total momentum of the liquid. In the third stage, when the rolling wave impacts the liquid surface, the employed methodology with two-dimensional solution and free-surface approach seems to reach its limits of applicability. A more complex modelling would be necessary to capture this phase of the impact properly.