Assessment of water depth change patterns in 120° sharp bend using numerical model

In this study, FLUENT software was employed to simulate the flow pattern and water depth changes in a 120° sharp bend at four discharge rates. To verify the numerical model, a 90° sharp bend was first modeled with a three-dimensional numerical model, and the results were compared with available experimental results. Based on the numerical model validation, a 120° bend was simulated. The results show that the rate of increase of the water depth at the cross-section located 40 cm before the bend, compared with the cross-sections located 40 cm and 80 cm after the bend, decreases with the increase of the normal water depth in the 120° curved channel. Moreover, with increasing normal water depth, the dimensionless water depth change decreases at all cross-sections. At the interior cross-sections of the bend, the transverse water depth slope of the inner half-width is always greater than that of the outer half-width of the channel. Hence, the water depth slope is nonlinear at each cross-section in sharp bends. Two equations reflecting the relationships between the maximum and minimum dimensionless water depths and the normal water depth throughout the channel were obtained.