Investigation of Flow Upstream of Orifices

Scour upstream of a circular orifice under constant head

“…13. For the fixed bed, the maximum velocity occurs close to the bed (Bryant 2006, Powell 2007. Within the scour hole, the location of the maximum velocity for the movable bed is higher and closer to the orifice centreline.…”

Discussion of “Discharge Coefficients for Orifices Cut into Round Pipes” by Alex J. McLemore, John S. Tyner, Daniel C. Yoder, and John R. Buchanan

“…On the first point of discussion, the paper cites a number of stateof-the-art reviews; however, some notable references (Smith and Walker 1923;Rov and Sen-Gupta 1940;Haghighi et al 1988;Miller 1978;Swamee and Jain 1976;Brater et al 1996;Bryant 2006;Bryant et al 2008;Werth et al 2005) are not referred to in the paper.…”

“…Studies conducted by Gregg et al (2003) and Werth et al (2005) on orifices in pressurized pipes for lateral outflow showed that the discharge coefficient (C d ) is a function of the approach velocity and the ratio of the orifice diameter (d) to the pipe diameter (D), in addition to the pressure in the pipe. Bryant (2006) investigated the flow pattern upstream of orifices in close proximity to the bed and surface; however, no comprehensive study of the discharge coefficient for orifices in riser pipes was carried out.…”

The effect of a plate installation upstream of an orifice on the pressurized flushing efficiency

“…Emamgholizadeh et al (2006) studied the D r a f t effect of sediment size on the pressurized flushing and found an increase in the flushing volume as the size of sediments changed from the coarse to fine grains. Through experimental studies, Bryant et al (2008) proposed a new method to solve flow pattern equations upstream of multiple, large, and small orifices. Meshkati et al (2009) investigated the effect of bottom outlet dimensions on the size of the flushing cone in the dam reservoirs.…”