The effect of convergence and divergence on flow pattern and sediment transport in lateral intakes using physical and numerical models

Abstract

Water supply at a desired rate at any time meet water requirements regardless of river discharge must be considered in the general design of intakes provided that the needs do not exceed the river flow. Due to the lack of necessary information in this field and the importance of sediment transport to lateral intakes at river bends, this study aimed at understanding the mechanism of this phenomenon. To this end, the combined effect of convergence and divergence in lateral intakes on sediment transport was investigated. According to the results, the diversion discharge to the intake increased by converging the laboratory flume. By narrowing and converging the end of the flume, the diversion discharge increased further so that as the flume converged to the size (b/B) of 0.75 and 0.5, the diversion discharge to the intake increased by 13.6% and 75%, respectively. This can be connected to narrowing, flow obstruction and backflow to the intake. In contrast, different results were found by diverging the flume. In other words, the inflow to the intake decreased by diverging the flume. As the flume end was diverged, the diversion discharge decreased further. By diverging the flume to the size (b/B) of 0.75 and 0.5, the diversion discharge to the intake decreased by 21.9 and 31.8%, respectively. The average diversion discharge to the intake at 30, 60 and 90° was 13.2, 15.2 and 11.5%, respectively. By converting the flume to the size (b/B) of 0.75 and 0.5, the diversion sediment to the intake increased by 18.5 and 71.4%. By diverging the flume to the size (b/B) of 0.75 and 0.5, the diversion sediment to the intake decreased by 35.4 and 49.9%, respectively. Comparison of the results with the mathematical model flow - 3D and CCHE2D was also performed, and the results were of good accuracy.

Keywords

• Intake
• Sediment transport
• Divergence
• Convergence
• Diversion discharge