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A Boussinesq-type model for flow over trapezoidal profile weirs

Author(s): Yebegaeshet T. Zerihun; John D. Fenton

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Keywords: Flow simulation; embankment weir; hydrodynamics; Boussinesq equation; rapidly varied flow

Abstract: Computational flow models that are developed based on the depth-averaged Saint–Venant equations cannot be used to simulate flow over shortand broad-crested trapezoidal profile weirs. In the derivation of the Saint–Venant equations, uniform velocity and hydrostatic pressure distributions have been assumed. These assumptions restrict the application of the equations to flow situations with insignificant curvature of streamlines. In this study a Boussinesq-type momentum equation, which allows for curvature of the free surface and a non-hydrostatic pressure distribution, along with a simplified equation for weakly curved free surface flow, are investigated for the numerical simulation of steady flow over short- and broad-crested types of these weirs with smooth and rough flow boundaries. The finite difference method is employed to discretize and solve these nonlinear flow equations. Computed and measured results of flow surface and bed pressure profiles for these types of weirs are presented. The Boussinesq-type momentum equation performs satisfactorily for both subcritical and transcritical flow situations, while the simplified equation simulates these flow situations on rough flow boundaries fairly well. The overall prediction results validate the use of the weak curvature approximation


Year: 2007

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