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Experimental and Numerical Investigation of Steady and Unsteady Flows in Roughened Channels with Cross Beams

Author(s): Christoph Gogolin; Rita Carvalho; Daniel B. Bung; Jorge Matos

Linked Author(s): Maria Rita L. M. F. Carvalho, Jorge Matos, Daniel B. Bung

Keywords: Channel flow; Energy dissipation; Drainage; Physical modelling; Numerical modelling

Abstract: In longitudinal drainage systems, high discharges may occur suddenly due to short, intense rainfalls. These high discharges and related high flow velocities lead to high shear stresses near the bottom and can thus cause significant damages to the structure. It is well known that the installation of cross beams enhances the energy dissipation along roughened channels (RCCB). In this work, we study the flow characteristics over cross beams in rectangular drainage systems; their height (5 and 10 cm) and spacing (0. 5, 1. 0, 1. 5 and 2. 0 m) were tested on a 5 % slope channel. Measurements of water depths based on an image processing technique were carried out for the different configurations in steady state conditions. The data is compared with numerical simulations as well as with recorded data of previous studies with slopes of 10 % and 15 % . The numerical results were obtained by the open-source code OpenFOAMTM. A fair agreement was found between numerical and experimental results. Moreover, for the present slope (5 % ) the effect of unsteady approaching flow on the water depths is investigated. Different scenarios for unsteady flow were tested applying diverse hydrographs and measurements were taken during the unsteady time interval.

DOI:

Year: 2013

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