Numerical study of the effect of non-continuous step on the residual energy of a vertical drop

Subject Areas : Analysis, design and construction of water structures

Samira Mazrouei ¹ , Reza Mirzaei ² , Shamsa Basirat ³ , Vadoud Hasanniya ⁴

1 - Department of Water Engineering and Hydraulic Structure, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran.
2 - Department of Water Engineering and Hydraulic Structure, Faculty of Civil Engineering, Semnan University, Semnan, Iran.
3 - Department of Civil Engineering, Islamic Azad University Najafabad, Isfahan, Iran
4 - Department of Water Engineering and Hydraulic Structure, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.

Received: 2023-07-03 Accepted : 2023-08-01 Published : 2023-09-04

Keywords: Downstream depth, Energy loss, non-Extended step, Turbulence, Vertical drop.,

Abstract :

In drainage and irrigation channels, vertical drop structures are commonly used to transfer water from a higher elevation to a lower one. At the downstream end of these structures, measures are taken to prevent channel bed erosion and reduce the destructive kinetic energy. In the present study, the effect of a non-extended step on the relative energy of the vertical drop structure was investigated using the FLOW-3D software and RNG turbulence model. Two relative heights and three relative widths for the step were considered, and the relative critical depth range was chosen between 0.2 and 0.5. The results indicate that the computed values of downstream relative depth show good agreement with experimental data. Additionally, both extended and non-extended step configurations yielded similar results, with an increase in the relative height of the step resulting in a reduction in the relative remaining energy. In other words, at a constant relative height of the step, for all critical relative depth values, the drop and turbulence generated in the plunge pool are the same for both extended and non-extended step models. Furthermore, employing a tranquility basin downstream reduced the wall height and length of the tranquility basin by more than 12% compared to the model without a step.

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