Numerical Study of Reducing the Flow Separation Zone in Short Open-Channel Expansions by Using a Hump
Publication: Journal of Irrigation and Drainage Engineering
Volume 142, Issue 7
Abstract
Subcritical flow in a short expansion tends to become detached from its sidewalls and create turbulent eddies. This phenomenon can cause undesirable losses of flow energy and channel erosion. This paper numerically investigates the effects of a triangular hump fitted at the bottom of the expansion on flow separation reduction. The results are validated using available experimental data. This paper reports quantitative details of the velocity field, eddy structures, and flow streamline separation in expansions of different divergence angles under various conditions of the Froude number. The results show that the flow of water can separate along either of the two sidewalls, possibly due to bistability. The use of appropriate humps can effectively reduce separation and turbulent eddies because they force the flow to accelerate and hence create a favorable pressure gradient. The results from this paper are useful for the optimal design of expansions as an important part of irrigation and water systems.
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Acknowledgments
This paper received financial support from NSERC of Canada through Discovery Grants held by S. Li.
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Information & Authors
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Published In
Journal of Irrigation and Drainage Engineering
Volume 142 • Issue 7 • July 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Aug 27, 2015
Accepted: Jan 26, 2016
Published online: Apr 4, 2016
Published in print: Jul 1, 2016
Discussion open until: Sep 4, 2016
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