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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : Evaluation of a depth-averaged numerical model in simulation of side weir overflow variations due to...
Evaluation of a depth-averaged numerical model in simulation of side weir overflow variations due to bed morphology changes
Author : MOHAMMAD ROSTAMI
ABSTRACT
Side weirs, also known as a lateral weirs, and overflow dams are free overflow regulation and diversion devices commonly
encountered in hydraulic engineering. They are set into the side of a channel or river allowing to spill a part of the
discharge over their crest when the surface of the flow in the main-channel exceeds a certain level. The lateral loss of
water is reducing the sediment transport capacity in the main-channel yielding to aggradation and the formation of a local
sediment deposit in the downstream weir alignment. The reduced cross section generates backwater effects and
additional contraction and expansion losses. As a consequence, the head over the side weir rises and the side overflow
discharge as well. The design discharge to be diverted over the weir is increased by this flow-sediment transport
interaction. Based on the systematic experimental flume study a two dimensional sediment transport model, CCHE2D, for
the prediction of the mobile bed evolution near the side weir have been used. The Numerical model allows a simple and
straightforward estimation of the interaction of a side overflow with bed-load transport and bed morphology in engineering
practice. Regarding the impact of the deposit on the intensity of side overflow it has been found out that the spilled
discharge might increase by a factor of up to 1.5 compared to fixed plane bed conditions. In this context about 25 % of the
total increase are attributed to effects of form roughness and about 75 % to bed aggradation phenomena. In this regard
the height of the deposit represents the most important parameter. Comparison between experimental data and numerical
modeling showed to be in a good agreement
File Size : 655,489 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 19/08/2015
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