Numerical Investigation of Shallow-Water Dam Break Flows in Open Channels and Dambreak-Induced Flood Using Smoothed Particle Hydrodynamics
Date Issued
2011
Date
2011
Author(s)
Kao, Hong-Ming
Abstract
A meshless numerical model is proposed to investigate shallow-water dam break flows in 1D open channels and 2D dambreak-induced flood and inundation. The numerical model is to solve the shallow water equations (SWE) based on smoothed particle hydrodynamics (SPH). The Lagrangian concepts of slice water particles (SWP) and cylindrical water particles (CWP) are adopted in the 1D SPH-SWE and 2D SPH-SWE formulations to generate horizontal flows and water surface variations in rivers and floodplains. The numerical sensitivity analysis is first performed to study the appropriate SWP/CWP number through dam break flows in an idealized 1D channel with dry-wet beds/through dam break flows in a dry flat floodplain.
Extensive 1D validation by comparison with laboratory and field data is next conducted for four benchmark problems, including dam break flows through a rough flat channel, a rough bumpy channel with various downstream boundary conditions, and a nonprismatic channel. Then five numerical validations are next described to demonstrate the benefits and limits of the 2D-SPH-SWE modeling, including laboratory dam break flows through a dry 45°bend channel, a flat floodplain with an isolated building, and field dam break flows over the scale models of the Toce river valley in Italy and the Reyran river floodplain in France.
The simulated results indicate that accurate performance is reached in the presence of shock discontinuities, shock front motion, hydraulic jumps, dry/wet bed flow, supercritical/subcritical/transcritical flow, reverse flow, contraction flow, overtopping flow, partial reflections and multiple wave interaction. A special attention is focused on the numerical performance of dealing with free-surface discontinuities, wetting and drying moving boundaries, and complex topography variations in rivers and floodplains. Thus, the proposed SPH approach has proved its efficiency and reliability for dam break flow computations in open channels and 2D flood and inundation problems.
Subjects
Smoothed particle hydrodynamics
Shallow water
Dam break flows
open channels
Flood and Inundation
Type
thesis
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