Numerical and analysis effects of rectangular prism rough beds on hydraulic jumps in open channels

Abstract

A hydraulic jump is a highly turbulent flow that causes significant turbulence and generates efficiency energy loss in the open channel. This research used the Flow-3D model, which combines the renormalization group RNG k-ε turbulent model and the volume of fluid (VOF) method, to investigate the hydraulic jump characteristics on rectangular prism rough beds. The results indicated that the rough beds had positively affected the hydraulic jumps. Specifically, the conjugate depth and jump length are reduced by about 17% and 50%, respectively, compared to the classical jump. In addition, the vorticity production rates are also used to clearly explain energy dissipation, which shows that the rough bed configuration significantly influences the hydraulic jump length. The results clarify the relationship between the hydraulic jump characteristics and the rough bed types studied. Moreover, this research provides valuable guidelines for choosing the geometrical features of the rough bed when designing or repairing the stilling basin for irrigation works and highway sewers downstream.