Experimental study of flow converging section side weir hydraulics

Side weirs are used to control water levels as well as water diversion for various uses in canals and rivers. Due to the complexity of flow conditions inside weirs, in this study, in order to simplify the calculations and increase its efficiency, this structure was investigated in convergent channel conditions. To investigate this issue, different geometric parameters of weir and hydraulic currents were investigated. Based on the geometric parameters of the side weir, experimental scenarios were considered. Based on the scenarios, 5 side weir lengths, 4 side weir heights, and 3 downstream channel widths were considered as side weirs that were tested at different discharges. Due to the fact that different geometric and hydraulic parameters were assumed to be variable in these experiments, the effect of each on the structure was analyzed and solutions for selecting the optimal dimensions in the channel were introduced. Based on the experimental results, it was found that for a fixed upstream water height with a 19% reduction in the width of the downstream channel, the ratio of the flow deflection to the lateral channel increases by 30%. It should be noted that the change in the flow section by converging the passage channel causes the longitudinal profile of the water surface to have a minimum height fluctuation along the entire length of the structure.