Reverse flow downstream multi-vent regulators

Flow separation is a natural phenomenon encountered for some cases in the non-prismatic stilling basins of irrigation works. The main flow is divided into two main jets as forward and reverse flows. When this happens, a plane of separation zone is formed in the downstream channel, which can be considered as a solid surface. The percentage area of reverse flow must be taken into consideration downstream regulators, because its negative effect on flow characteristics. An extensive experimental program has been conducted on a model simulating Assuite Barrages in Hydraulic Research Institute (HRI). It is found that the percentage area of reverse flow is dependent on the expansion ratio and the Froude number under gates, but the major effect is on the expansion ratio. Statistical model was developed, to predict the percentage area of reverse flow. It is recommended to control the area of reverse flow by control facilities which distribute the flow uniformly in lateral direction.