Numerical study of submerged hydraulic jumps over triangular macroroughnesses

Abstract

The hydraulic jump is a phenomenon that occurs in open channels. In past studies, hydraulic jumps over smooth and macrorough beds have been investigated to enhance energy dissipation, but triangular macroroughness, specifically the right-angled triangular macroroughness, has not been dealt with. The objective of this article is to numerically investigate submerged hydraulic jumps over right angle and isosceles triangular macrorough beds. To achieve this, a numerical model based on computational fluid dynamics (CFD) has been utilized. Numerically obtained jump characteristics such as submerged depth ratio, tailwater depth ratio, longitudinal velocity profile, flow pattern in the cavity region, and energy dissipation have been presented in detail. In particular, initial Froude number reduction in both tailwater and submerged depth ratios as well as an increase in the energy dissipation of submerged hydraulic jumps have been noticed on isosceles triangular macroroughness with different arrangements, as compared to smooth beds. The present numerical model has been validated with the experimental model, and the mean error between the two for submerged depth and tailwater depth ratios was found to be below 6%. This confirms the adequacy of the present CFD model in predicting relevant submerged hydraulic jump characteristics over macrorough beds.