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Secondary-Current Impact on Momentum Transfer for Compound Channels Flow Modelling

Author(s): Didier Bousmar; Yves Zech

Linked Author(s): Yves Zech, Didier Bousmar, K.L. Meijer

Keywords: Compound channels; Floodplains; Secondary currents; Dispersion; Depth-averaged; Numerical modelling

Abstract: Coherent turbulence structures are responsible for large momentum transfer in compound channels. Large vortices, with vertical axis, located at the shear layer between the main channel and the floodplains generate the main momentum transfer and can be adequately captured through depth-averaged Large Eddy Simulation. This momentum is supposed to be transported on the floodplains through secondary currents. Due to those secondary currents, the velocities computed with the actual friction factor of the channel are generally underestimated when compared with the measured ones. This paper presents an attempt to take into account the secondary-current effects in a depth-averaged numerical simulation, through adequately modelled dispersion terms. The velocity profile prediction can be greatly improved, but the physical meaning of the necessary dispersion coefficients has to be deepened.


Year: 2001

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