Numerical Investigation of Hydraulic Characteristics of Vertical Drops with Screens and Gradually Wall Expanding

In the present study, the hydraulic characteristics of vertical drops with screens and the gradual wall expanding downstream using FLOW-3D software are investigated. For this purpose, two porosity ratios of the screens of 40 and 50%, 5 gradually expanding with 3 vertical drop heights in the specified discharge range were used. It was found that the numerical results are closer to the experimental results with the RNG turbulence model than k-ε. By increasing the drop height, the ΔE/E0 due to the jet floor impact intensity increased and yp/P value decreased. The maximum ΔE/E0 for 25 cm height was 51.60% and the lowest for 15 cm was 44.25%. For a constant drop height with increasing discharge, the ΔE/E0 decreased and yp/P increased. The gradually wall expanding causes turbulence on the edges and a non-uniform distribution of yd/P and by increasing yp/P and yd/P, it caused a 25% increase in ΔE/E0. The presence of screens increased yp/P, yd/P, and ΔE/E0 by 44%. The simultaneous use of gradually walls expanding and screens caused a 46% increase in ΔE/E0 and a decrease in yp/P and yd/P values. It was shown that the contribution of screens is greater than the gradually wall expanding, with their simultaneous application increasing ΔE/E0 up to 33.5%.