Optimizing Roughness Parameters for Enhanced Hydraulic Jump Control in Ogee Spillway Stilling Basins

Articles in Press

Document Type : Original Article

Authors

1 PhD of Water Rwsource Engineering, Sceince & Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Civil Engineering, Bey. C., Islamic Azad University, Beyza, Iran

10.22044/jhwe.2026.16584.1075

Abstract

This research investigates how surface roughness—characterized by the height and spacing of roughness elements—affects hydraulic jump behavior within the stilling basin downstream of an Ogee weir. Using Fluent numerical simulations, the study examines flow structures and geometric configurations around the weir, with the computational findings validated against experimental measurements obtained from a physical model constructed at the Islamic Azad University of Yasuj. The results demonstrate that the introduction of bed roughness markedly alters the characteristics of the hydraulic jump. Increasing the height of roughness elements consistently decreases the jump length and lowers the ratio of secondary to primary flow depth, a response attributed to the modified turbulence structure and enhanced energy loss induced by the roughened surface.

More specifically, the optimal arrangement—roughness elements 2 cm in height with a 2 cm spacing—was shown to shorten the hydraulic jump length by up to 40% and improve energy dissipation by approximately 35% in comparison with a smooth bed. The numerical simulations exhibited excellent consistency with laboratory observations, yielding a maximum deviation of only 0.02% in predicted water surface profiles. These quantitative outcomes confirm the strong reliability of the modeling approach and offer engineers a clear basis for designing more compact and efficient stilling basins. Strategically incorporating roughness of suitable dimensions, particularly in MVSP channels, enables the development of cost-effective structures that maintain—or even enhance—hydraulic performance. Overall, the study significantly advances understanding of how surface roughness influences hydraulic jump dynamics and provides practical design guidance for optimizing energy dissipation in modern hydraulic systems.

Keywords

Journal of Hydraulic and Water Engineering

Articles in Press, Accepted Manuscript
Available Online from 17 July 2026

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