Numerical hydraulic modeling of the flow in the composite structure of the multiple rectangular Lopac Gate with gradual transformation

Document Type : Original Article

Authors

1 Department of Water structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

2 Department of Water structures, Faculty of Water and Environmental Engineering , Shahid Chamran University of Ahvaz, Ahvaz, Iran.

3 Department of Water structures, Faculty of Water and Environmental Engineering , Shahid Chamran University of Ahvaz , Ahvaz, Iran .

4 Department of Water structures , Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

Abstract

Objective: This comprehensive study systematically evaluates the hydraulic characteristics of multi-rectangular Lopac gates incorporating gradual transformation features, with particular emphasis on their comparative performance against traditional non-transformed gate designs.
 
Method: Through detailed experimental analysis under controlled flow conditions (20–60 L/s), the hydraulic behavior of multi-rectangular Lopac gates with 5° and 10° transformation angles was investigated at gate openings of 30°, 45°, and 60°. Shear stress distribution, discharge characteristics, flow coefficients, and vortex dynamics were evaluated using detailed flow visualization studies.
 
Results: For shear stress distribution, the 5° transformed configuration demonstrated substantial reductions of 27%, 13%, and 10% in maximum floor stress at gate openings of 30°, 45°, and 60°, respectively. Conversely, the 10° transformation increased floor stresses by 53%, 21%, and 24% at corresponding openings. The 5° transformation enhanced flow coefficients by 2.4%, 3.0%, and 3.4% for 30°, 45°, and 60° openings, respectively, while the 10° transformation yielded improvements of 8%, 13%, and 10%. Flow visualization showed that transformed gates produce larger, more organized vortices with reduced frequency, whereas conventional designs generate numerous smaller and more chaotic vortices.
 
Conclusions: The findings show that gradually transformed multi-rectangular Lopac gates improve stress distribution, flow efficiency, and vortex control. The 5° transformation reduces floor stress, while the 10° transformation improves flow coefficients but increases stress. An optimal transformation angle between 5° and 10° may further enhance gate performance.

Keywords

Main Subjects

References

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Advanced Technologies in Water Efficiency
Volume 6, Issue 3
September 2026
Pages 1-25

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  • Receive Date: 15 July 2025
  • Revise Date: 11 November 2025
  • Accept Date: 27 December 2025

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