3D NUMERICAL MODELING OF DAM-BREAK FLOOD IN AN URBAN LOCALITY

Abstract

This thesis presents a novel methodology for urban flood risk assessment, leveraging a state of-the-art 3D urban flood modeling technique. Utilizing the Volume of Fluid (VOF) method within ANSYS Fluent, this approach innovatively simulates and analyzes complex flooding scenarios in urban environments. The model's accuracy is critically evaluated using the Mean Absolute Relative Error (MARE), ensuring precise and reliable results. At the heart of this study is an in depth analysis of three variations of the K-epsilon turbulence model: Standard, RNG (Re Normalization Group), and Realizable. Each is rigorously tested within the context of the 'Model City Flooding Experiment', providing a comprehensive comparison. The research further explores the influence of urban building configurations, examining both aligned and staggered layouts, and their effects on flood behavior. Advanced statistical methods, including Nash-Sutcliffe Efficiency (NSE) and the R2 coefficient of determination, are employed to validate the superior performance of the Realizable K-epsilon model in capturing urban flooding complexities. Additionally, a sensitivity analysis is conducted, focusing on the interaction between key factors such as the roughness model, the choice of turbulence model, and the level of grid refinement. This analysis reveals that increased roughness height, implementation of the K-epsilon model, and a denser grid significantly enhance the model’s fidelity, albeit increasing the simulation time. This research not only introduces a sophisticated tool for refined urban flood risk assessment but also lays the groundwork for future enhancements in the precision and application of urban flood models, especially in complex terrains prone to rapid or dam-break flooding. Keywords: ANSYS; numerical Simulation; Computational fluid dynamics (CFD); Urban flooding; 3D flood inundation modeling; flash flood experiment