Experimental Investigation of the Characteristics of a Hydraulic Jump Controlled by a Positive Step in a Rough-Bed Channel

Abstract

This paper presents an experimental investigation of a hydraulic jump controlled by a positive step evolving in a rectangular channel with a rough bottom. The study focuses on the combined effects of bed roughness and step height on the main hydraulic characteristics of the jump, namely the conjugate depth ratio, the relative jump length, the relative step height, and the energy dissipation efficiency. Experiments were carried out in a horizontal laboratory flume equipped with interchangeable rough beds and positive steps of varying heights. The results show that increasing bed roughness significantly enhances energy dissipation and reduces jump length, while the positive step effectively stabilizes and controls the jump position. Empirical dimensionless relationships are proposed and validated, providing practical tools for the design of compact energy dissipation basins.