An Experimental Investigation of the Relative Length of Hydraulic Jump in a Rectangular Channel with a Composite Section, Featuring a Rough Major Bed and Positive Slope

Hydraulic jumps occur when the flow shifts from supercritical to subcritical, forming a standing wave with a sudden increase in the water surface elevation in the channel. This transition gives rise to a turbulent zone, where surface rollers are generated, leading to vigorous water mixing, air entrainment, and significant dissipation of water energy. The present study deals with hydraulic jumps in a rectangular channel, having a composite section characterized by a rough major bed (made of uniform plastic granules) and a positive slope under various flow circumstances. The hydraulic characteristics were assessed for varying bed roughness and positive slopes, focusing on the relative length of the hydraulic jump (Lj/h1) and flow rate. The experimental data analysis revealed that the roughness of the main bed and the channel slope affect the Lj/h1 ratio. The extensive data on the hydraulic jumps in rough channel beds have facilitated the development of mathematical models to represent the Lj/h1 ratio as a function of roughness and slope factors.