Author(s): Weiming Wu; Sam S.Y. Wang

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Keywords: Transient flow; overtopping flow; dam-break flow; sediment transport; erosion; movable bed; one-dimensional model; finite

Abstract: A 1D finite-volume model has been established to simulate the nonequilibrium transport of nonuniform sediment with transient flows, such as dam-break flow and overtopping flow, over movable beds. The effects of sediment transport and bed change on the flow are considered in the flow continuity and momentum equations. An explicit algorithm is adopted to solve the governing equations. The model has been tested preliminarily in several experimental cases, including an experiment on wedge development due to sediment overloading under transcritical flow conditions, an experiment on dam surface erosion due to overtopping flow, and two experiments on dam-break flow over movable beds. The model performs quite well in the cases of wedge development and overtopping flow, but significantly under-predicts the bed erosion due to dam-break flow. A modification has thus been made by considering the effects of sediment concentration on sediment settling and entrainment in the case of dam-break flow over movable beds. The present model has been compared with the traditional movable-bed “clear-water” model that ignores the effects of sediment on the flow. It has been found that the present model provides more reasonable predictions, and the “clear-water” model has larger errors when sediment transport is stronger and may even fail in the case of dam-break flow.

DOI: https://doi.org/10.1080/00221686.2008.9521846

Year: 2008