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In this paper, the inclined side weir discharge coefficient was studied using a side weir with three different
crest angles (θ = 4°, 8°, 12°) fixed either against and in the flow direction, and the results are compared
with those from a horizontal side weir crest (θ = 0°). In total there were seven models.
The results show that the De Marchi assumption of constant energy for all side weir crested angles is
acceptable, and thus that the calculated weir discharge value can therefore be undertaken.
An equation for the discharge coefficient was obtained for an inclined side weir, so the value of Cd for
crest angle θ = 12° increased by 13.6% with respect to the value for θ = 8°, by 29% with respect to that
for θ = 4°, and by 39% with respect to that for the horizontal case (θ = 0°), for a crest inclined against the
flow direction, while when the crest was inclined in the flow direction all those values exceed, to 14.5%,
31.0%, and 40.7%, respectively. This means that the discharge increases with increasing side weir crest
angle, so when we want uniformity in the flow direction and exceed discharge we need to make the side
weir crest incline against the flow direction while when we want furthermore discharge we need to make
the side weir crest incline in the flow direction.