Discharge coefficient for an inclined side weir crest using a constant energy approach

In this paper, the inclined side weir discharge coefficient was studied using a side weir with three different crest angles (theta = 4 degrees, 8 degrees, 12 degrees) fixed either against and in the flow direction, and the results are compared with those from a horizontal side weir crest (theta = 0 degrees). 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 C-d for crest angle theta = 12 degrees increased by 13.6% with respect to the value for theta = 8 degrees, by 29% with respect to that for theta = 4 degrees, and by 39% with respect to that for the horizontal case (theta = 0 degrees), 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. (C) 2011 Elsevier Ltd. All rights reserved.