Analytical Approach for Flow over an Oblique Weir


Department of Civil Engineering,Isfahan University of Technology


Flow discharge over an oblique weir is greater than that over a straight or plain weir for
the same water head due to its extra length with respect to the channel width or fully extended plain weir.
In this study, a new theoretical approach is used for the hydraulics of oblique weirs. The main objective
is to investigate the e ect of di erent hydraulic and geometric properties of the
ow and the weir on
ow de
ection angle and discharge coecients for free and submerged
ow over oblique weirs. This
approach is based on energy, momentum and continuity equations. For improving the performance of this
kind of weir, one approach is to increase the
ow de
ection until it is perpendicular to the oblique weir
for maximum use of the weir length. The submerged guide vanes have also been used and investigated
theoretically. The data for calibration of the models are taken from Borghei et al.(2003). It is shown that
by employing guide vanes, for some cases, the discharge coecient can be increased up to 33%. Finally,
new relations were developed for practical purposes.