EFFECTS OF OPEN-CHANNEL GEOMETRY ON FLOW PATTERN IN A 90° JUNCTION

Abstract

Open-channel junctions have a broad application in civil and environmental engineering. Formation of a low-pressure zone with recirculating flow (high sedimentation) accompanied by a high-velocity zone (high erosion) is the most characteristic feature of flow in junctions. A large number of researches have been performed to study the complexity of the flow in junctions in open-channel flows. In this research, four new geometrical modifications, based on streamlinization concept, are investigated to understand their effects on reducing the sedimentation and erosion potential in a 90° open-channel junction. First, the numerical model was validated based on previous experimental studies. Then, effects of the mentioned modifications were evaluated and some efficiency measures were devised to improve their performance. The results show that employing the proposed geometrical modifications improves the flow pattern significantly via eliminating the recirculation zone and reducing the maximum flow velocity after the junction. Thereby a comprehensive reduction in sedimentation and erosion potential is produced as well as contracting the stagnation zone.