The performance of hydraulic jump over rough bed stilling basin consisting of cubic-shape elements

Abstract

Three groups of cubic roughness elements non-protruding to the flow were fixed with a specific configuration at the downstream of a stream lined lib sluice gate. The aim was to test the performance of the hydraulic jump under using such elements as appurtenances of stilling basin. The experimental works has been conducting to test; four different intensities, I=8%, 10%, 12% and 16%; three width to height ratios, We/he=0.75, 1.5 and 2; and three length to height ratios, Le/he=0.75, 2 and 4, of cubic elements made from waterproof stiff rubber. The test was performed under the incoming Froude number; F1 ranged between 2.7 to 9. After analysing the experimental data one from the second group configuration gives a higher reduction of sequent depth ratio, y2/y1 as compared with the depth ratio of the un-forced hydraulic jump which calculated by Belanger equation, this decreases arrived 20%. Also greater relative energy has been dissipated, and the gain in dissipation (%GED) ranged between 10.8-22.3%.