Discharge Coefficient for Sharp-Crested Side Weir in Subcritical Flow
Publication: Journal of Hydraulic Engineering
Volume 125, Issue 10
Abstract
To estimate the outflow over a rectangular sharp-crested side weir, the discharge coefficient in the weir equation needs to be known. Although this type of structure has been designed and used extensively by hydraulic engineers, a universally acceptable discharge coefficient does not exist. In this study over 250 laboratory tests were conducted, and the results were analyzed to find the influence of the flow hydraulics and the geometric, channel, and weir shapes on the coefficient. The results show that for subcritical flow the De-Marchi assumption of constant energy is acceptable, and the weir discharge can therefore be used. Furthermore, it was discovered that the De-Marchi coefficient of discharge is a function of the upstream Froude number and the ratios of weir height to upstream depth and weir length to channel width, whereas the channel slope in subcritical flow can be ignored. Hence, an accurate equation for the coefficient of discharge is introduced.
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Information
Published In
Journal of Hydraulic Engineering
Volume 125 • Issue 10 • October 1999
Pages: 1051 - 1056
History
Received: Dec 8, 1997
Published online: Oct 1, 1999
Published in print: Oct 1999
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