Free Overfall in Inverted Semicircular Channels
This article has a reply.
VIEW THE REPLYPublication: Journal of Hydraulic Engineering
Volume 129, Issue 6
Abstract
This paper presents a theoretical and experimental study on free overfall in a smooth inverted semicircular channel. Applying the momentum equation based on the Boussinesq approximation, the flow upstream of a free overfall is theoretically analyzed to calculate the end-depth-ratio (EDR). This approach eliminates the need of an empirical pressure coefficient. In subcritical flows, the EDR related to the critical depth is found to be 0.705 for critical depth-diameter ratio up to 0.42. In supercritical flows, the Manning equation is used to express the end-depth as a function of the streamwise slope of the channel. Methods to estimate discharge from the end-depth in subcritical and supercritical flows are presented. The discharge is also related to the end-depth and a characteristic parameter of the channel. The upstream free surface profiles are computed using the streamline curvature at free surface. The computed and experimental results are in satisfactory agreement in subcritical flow and have a slight discrepancy in supercritical flow.
Get full access to this article
View all available purchase options and get full access to this article.
References
Anastasiadou-Partheniou, L., and Hatzigiannakis, E.(1995). “General end-depth-discharge relationship at free overfall in trapezoidal channel.” J. Irrig. Drain Eng., 121(2), 143–151.
Anderson, M. V.(1967). “Non-uniform flow in front of a free overfall.” Acta Polytech. Scand., Civ. Eng. Constr. Ser., 42, 1–24.
Davis, A. C., Ellett, B. G. S., and Jacob, R. P.(1998). “Flow measurement in sloping channels with rectangular free overfall.” J. Hydraul. Eng., 124(7), 760–763.
Dey, S.(1998a). “Free overfall in rough rectangular channels: a computational approach.” Proc. Inst. Civ. Eng., Waters. Maritime Energ., 130(Mar.), 51–54.
Dey, S.(1998b). “End depth in circular channels.” J. Hydraul. Eng., 124(8), 856–863.
Dey, S.(2000). “End depth in steeply sloping rough rectangular channels.” Sadhana, Proc. Indian Acad. Sci., 25(Feb.), 1–10.
Dey, S.(2001a). “EDR in circular channels.” J. Irrig. Drain Eng., 127(2), 110–112.
Dey, S.(2001b). “Flow metering by end-depth method in elliptic channels.” Dam Eng., 12(1), 5–19.
Dey, S.(2002a). “Free overfall from circular channels with flat base.” Flow Meas. Instrum., 13(5–6), 209–221.
Dey, S.(2002b). “Free overfall in open channels: state-of-the-art review.” Flow Meas. Instrum., 13(5–6), 247–264.
Dey, S.(2003). “Overfall in U-shaped channels.” J. Eng. Mech., 129(3), 358–362.
Dey, S., and Ravi Kumar, B.(2002). “Hydraulics of free overfall in Δ-shaped channels.” Sadhana, Proc. Indian Acad. Sci., 27(June), 353–363.
Ferro, V.(1992). “Flow measurement with rectangular free overfall.” J. Irrig. Drain Eng., 118(6), 956–964.
Ferro, V.(1999). “Theoretical end-depth-discharge relationship for free overfall.” J. Irrig. Drain Eng., 125(1), 40–44.
Hager, W. H.(1983). “Hydraulics of the plane overfall.” J. Hydraul. Eng., 109(12), 1683–1697.
Hager, W. H.(1999). “Cavity outflow from a nearly horizontal pipe.” Int. J. Multiphase Flow, 25(2), 349–364.
Henderson, F. M. (1966). Open channel flow, MacMillan New York.
International Organization for Standardization (ISO) 3874. (1977). “End depth method for estimation of flow in rectangular channels with a free overfall.” International Organization for Standardization, Geneva, Switzerland.
ISO 4371. (1984). “End depth method for estimation of flow in non-rectangular channels with a free overfall.” International Organization for Standardization, Geneva, Switzerland.
Jaeger, C. (1957). Engineering fluid mechanics, St. Martin’s Press, New York.
Keller, R. J., and Fong, S. S.(1989). “Flow measurements with trapezoidal free overfall.” J. Irrig. Drain Eng., 115(1), 125–136.
Marchi, E.(1993). “On the free overfall.” J. Hydraul. Res., 31(6), 777–790.
Montes, J. S.(1992). “A potential flow solution for the free overfall.” Proc. Inst. Civ. Eng., Wates, Maritime Eng., 96(Dec.), 259–266.
Murty Bhallamudi, S.(1994). “End depth in trapezoidal and exponential channels.” J. Hydraul. Res., 32(2), 219–232.
Naghdi, P. M., and Rubin, M. B.(1981). “On inviscid flow in a waterfall.” J. Fluid Mech., 103, 375–387.
Rajaratnam, N., and Muralidhar, D.(1964). “End depth for exponential channels.” J. Hydraul. Div., Am. Soc. Civ. Eng., 90(1), 17–36.
Rouse, H.(1936). “Discharge characteristics of the free overfall.” Civ. Eng. (N.Y.), 6(4), 257–260.
Information & Authors
Information
Published In
Copyright
Copyright © 2003 American Society of Civil Engineers.
History
Received: Jan 30, 2001
Accepted: Dec 17, 2002
Published online: May 15, 2003
Published in print: Jun 2003
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.