Author(s): K. Shiono; J. Spooner; P. Rameshwaran; J. H. Chandler
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Keywords: Meandering channel; Flat bed; Mobile bed; Flow structure; Energy loss; Turbulence
Abstract: Measurements of mean velocity and secondary flow, in meandering channels with flat bed and natural formed bed for overbank, were carried out using Laser Doppler Anemometer. Bed-forms were also measured using automated digital photogrammetry. This enabled the evolution of secondary flow to be identified within the meandering channel. Detailed measurements of secondary flow along a sand bar were also carried out for understanding the interaction between secondary flow and the bed form caused by floodplain flow. A comparative study of flow structures in the meandering channels with flat and mobile beds for overbank flows, was carried out using layer-averaged velocities, longitudinal mean velocities and secondary flow vectors along the meandering channel. The Reynolds stresses on the horizontal plane at bankfull level were measured in order to calculate energy loss owing to turbulence. Energy losses due to secondary flow, turbulence and boundary friction within the main channel were estimated. This result demonstrated significant energy losses due to secondary flow and boundary friction for the natural formed bed case. However, for the flat bed case boundary friction loss is dominant and turbulence loss is relatively significant, but secondary flow loss is small.
Year: 2001