Author(s): Rongfu Ning; Ruidi Bai; Hang Wang; Shanjun Liu
Keywords: Hydraulic jump; Vegetated bottom; Free surface fluctuation; Jump length
Abstract: Hydraulic jump is a characteristic hydraulic phenomenon that is the transformation from a supercritical flow to a subcritical flow. Previous studies indicate that the channel bed roughness has a significant effect on jump length, conjugate depth and air water flow properties. However, there is little literature referring to the turbulent characteristics in hydraulic jump on vegetated bottom. This paper presents an experimental investigation of hydraulic jump for a wide range of Froude numbers (5.73 < Fr1 < 9.67) at the relative Reynolds numbers (0.67 × 105 < Re < 1.12 × 105) on the open channel with one grate mat and two vegetation configurations, respectively. The free surface characteristics were systematically investigated ultrasonic displacement meters from the jump toe to far field region. Observations showed that the conjugate depth ratio of vegetated bed had in good agreement with smooth bed. The jump length decreased with increasing bottom roughness. While the maximum free surface fluctuation value was smaller than most previous literatures. The present study highlights significant effects of vegetated covers on flow performances of hydraulic jumps.