Laboratory evaluation of artificial roughness and adverse slope effect in control of hydraulic jump

Hydraulic jump is created at the end of shoots and many hydraulic structures. The occurrence of a hydraulic jump phenomenon leads to a decrease in the amount of energy in open channels. In the present study, in order to simultaneously evaluate the effect of roughness and the effect of reciprocal slope on reducing the secondary depth of the hydraulic jump, as well as reducing the length of the hydraulic jump.

In this study, two types of roughness in the form of rhombuses and triangles were compared in a laboratory with a reverse slope of zero to 0.1% compared to a flat surface. The results of experiments related to the effect of roughness in reducing the relative second depth of hydraulic jump showed that rhombic and triangular roughness (in the horizontal plane) were effective in reducing the relative depth of hydraulic jump by 9.6 and 9.1%, respectively. Also, the results related to the effect of reverse slope (at the surface without roughness) on controlling the relative second depth of hydraulic jump showed that creating and increasing the reverse slope in the tested interval alone will not have an effect on reducing the relative second depth of hydraulic jump.

After examining the effect of roughness and reverse slope in controlling the relative length of hydraulic jump, it was observed that at the highest rate, the relative length of hydraulic jump was reduced by 0.075% and the roughness of rhombic and triangular, by 52.8 and 56.8% was observed. Therefore, as a result of this research, it can be stated that if the goal is to reduce the secondary depth of the hydraulic jump, the best option to reduce the secondary depth of the hydraulic jump is to roughen the bed using triangular roughness.