Author(s): Hossein Mahdizadeh; Benedict D. Rogers; Peter K. Stansby
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Keywords: No Keywords
Abstract: In cities, flood waves may propagate over street surfaces below which lie complicated pipe networks used for storm drainage and sewage. The flood and pipe flows can interact at connections between the underground pipes and the street surface. This paper examines this interaction, solving the two-dimensional shallow water equations with a Godunovtype wave propagation scheme to model the flood wave hydrodynamics. Our shallow-water model has already been validated in one dimension for simulating vertical flows through finite gaps in the bed by comparing with a commercial Navier-Stokes solver (STAR-CD) which models the free-surface motions. Sources and sinks in the mass conservation equation are used to model the pipe inflow and outflow conditions at bed connections. This work has examined the interaction of vertical flows created by an underground sewage pipe with a dam break flow over either dry or wet beds, and a flood wave propagating over an underground connecting pipe with both an inlet and outlet. Using an efflux number, defined En=V/gl using the vertical efflux velocity, V, and gap length, l, the model gives sensible predictions at all times provided En 0. 5. This paper presents a fully two-dimensional shallow water scheme which models the interaction between the freesurface flow and the efflux/influx discharges created by underground pipe networks. The paper presents the validation results for two-dimensional efflux over dry state, then a two-dimensional dam-break flood wave interacting with a single efflux pipe. The paper finishes with the first two-dimensional shallow water simulation over a multiple efflux pipes.
Year: 2010