Building Treatments in Numerical Modeling of Dam Break Induced Flow in Urban Area

Abstract

Dam break is one of the most dangerous disasters, which cause a large mass of water from the reservoir is suddenly released to the downstream. Although dam break events are still rare, the occurrences can cause severe damage to the downstream area, especially if the downstream is an urban area. Urban flood due to dam break has a different characteristic compared to the flood in nature. Modeling the flood is good way to learn the urban flood characteristic. Therefore, further studies are needed to develop an urban dam break model. Numerical modeling is one of the most effective methods to simulate the flood. In numerical modeling, buildings can be modeled with 3 approaches, as a wall boundary, as an area with high manning value, and as a contour. This paper discusses about two-dimensional flow of a dam break which flows through a sloping channel and single building, particularly comparing 3 approaches to modeled the building. The case is based on laboratory experiment of previous study. The model was developed with 2D Shallow Water Equations (SWE) which are based on the conservation of mass and momentum derived from Navier Stokes equation. The equations then discretized using Mac-Cormack numerical scheme. Numerical filter is used to reduce the numerical instability or oscillation in the model. The numerical model results are then compared to the experimental result from previous study. The accuracy of the numerical model was checked using Root Mean Square Error (RMSE) to determine the best methods to modeled the building. The results indicate that modeling the building as a wall boundary have the best results with lowest RMSE value and also shown the closest comparison of water level compared to the experimental results. By conducting this study, it is hoped to assist the urban dam break modeling in the future.