Journal of New Approaches in Water Engineering and Environment
Scientific Journal

Experimental Study on the Influence of Transverse Jet Angle Variation with a Counter Jet on the Control of Asymmetric S and T Hydraulic Jumps

Document Type : Original Article

Authors

Mostafa Rahnamayi 1
javad ahadiyan 2
mahmood shafai bejestan 3
mohsen sajadi 1

1 Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. Center of Excellence of the Network Improvement and Maintenance, Ahvaz, Iran.

2 Faculty of Water Sciences Engineering ,Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. Center of Excellence of the Network Improvement and Maintenance, Ahvaz, Iran

10.22034/nawee.2025.498882.1130
Abstract
Objective: Using a water injection system with counter and transverse jets against the flow passing over an ogee spillway after a sudden expansion reduces pressure fluctuations and turbulence along the channel, resulting in flow uniformity and consequently controlling asymmetric jumps.
Methods: In this research, the hydrodynamic flow parameters in a channel were investigated using a combination of a transverse jet at angles of 30, 45, and 90 degrees at two heights of 35 and 45 cm from the channel bed, and the simultaneous use of a counter jet with 5 fixed jets and a total discharge of 4 liters per second, with three Froude numbers of 4.7, 7.8, and 9.5.
Results: The jet injection time, the βL parameter (a parameter similar to the Boussinesq coefficient in the momentum equation) in the S jump exhibits less turbulence and dispersion compared to the T jump, indicating that the use of a transverse jet injection system can act as a flow dissipater, leading to flow uniformity. It also causes a significant reduction in the flow momentum (βL.Vm²) at the sudden expansion section from the beginning to the end of the channel.
Conclusions: The use of a transverse and counter jet system with varying angles can significantly reduce turbulence and channel erosion, control asymmetric hydraulic jumps, and uniformize the flow velocity distribution along the channel.

Keywords

Counter &‌ Transverse jets
S &‌ T-type hydraulic jump
Energy dissipater
Sudden expansion
Journal of New Approaches in Water Engineering and Environment
Volume 5, Issue 1
February 2026
Pages 143-161

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