Author(s): Burhhan Yildiz; Wim Uijttewaal
Linked Author(s): Wim S.J. Uijttewaal
Keywords: Open channel flows; Weir flow; Horizontal shear; Head loss
Abstract: Compound weirs can be used as flexibly adjustable structures to regulate the flow and its distribution over the cross-section. Examples are found as control structures in rivers, for example to regulate water levels or to create additional resistance in one side of the river bifurcations. It is done to distribute the discharge among the tributaries properly. They are placed at the flood plains and become active only during flooding. Therefore, the expected flow type over the weirs is generally submerged, unlike the modular weir flow which has been studied a lot in the literature (Bos 1989). As the crest levels of a compound weir vary of the flow width, the discharge per notch varies resulting in a non-uniform velocity profile upstream and downstream of the structure. The associated hydrodynamic interactions give rise to additional losses in velocity gradients, flow contraction and expansion. It is therefore doubtful whether the discharge of a compound weir can be estimated as the sum of the independent discharges of the individual notches. The goal of this study is to find out for what conditions a standard approach is valid and when the horizontal non-uniformity should be accounted for.
Year: 2025