In this work, a numerical model of one dimensional, mobile bed, dam break flow is described and tested. As usual in this field, the dam is schematized to be a vertical wall that instantaneously disappears. Due to the fact that the bed is a mobile one, the flow induced by such a disappearing causes localized erosion at the dam site, and intense suspended sediment transport occurs. The phenomenon is simulated using a mathematical model, consisting of a set of four differential equations in a shallow water frame. Accuracy and stability problems due to the strongly time varying character of the flow and to the different aspects linked to the dry bed propagation phenomena are kept under control, including the fast rate of change in bed elevation. Two different schemes are compared, which are a Beam Warming three-Point Backward implicit finite difference method and a Godunov-type, Total Variation Diminishing, explicit finite volume method. Numerical results are compared with recent laboratory results, that put into evidence how the strong erosion at the dam site causes the formation of an hydraulic jump just at the dam location. The formation of the jump is captured by the numerical codes, and also the maximum amplitude of the erosion is reproduced. Robustness, stability and conservation properties of the scheme are shown to be saved.

Dam break modeling for sediment laden flows

VALIANI, Alessandro;CALEFFI, Valerio
2001

Abstract

In this work, a numerical model of one dimensional, mobile bed, dam break flow is described and tested. As usual in this field, the dam is schematized to be a vertical wall that instantaneously disappears. Due to the fact that the bed is a mobile one, the flow induced by such a disappearing causes localized erosion at the dam site, and intense suspended sediment transport occurs. The phenomenon is simulated using a mathematical model, consisting of a set of four differential equations in a shallow water frame. Accuracy and stability problems due to the strongly time varying character of the flow and to the different aspects linked to the dry bed propagation phenomena are kept under control, including the fast rate of change in bed elevation. Two different schemes are compared, which are a Beam Warming three-Point Backward implicit finite difference method and a Godunov-type, Total Variation Diminishing, explicit finite volume method. Numerical results are compared with recent laboratory results, that put into evidence how the strong erosion at the dam site causes the formation of an hydraulic jump just at the dam location. The formation of the jump is captured by the numerical codes, and also the maximum amplitude of the erosion is reproduced. Robustness, stability and conservation properties of the scheme are shown to be saved.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1196363
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