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 (Department of Water Engineering and Hydraulic Structure, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran.)
Reza Mirzaei ² (Department of Water Engineering and Hydraulic Structure, Faculty of Civil Engineering, Semnan University, Semnan, Iran.)
Shamsa Basirat ³ (Department of Civil Engineering, Islamic Azad University Najafabad, Isfahan, Iran)
Vadoud Hasanniya 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.

References:

Bagherzadeh, M., Mousavi, F., Manafpour, M., Mirzaee, R., & Hoseini, K. (2022). Numerical simulation and application of soft computing in estimating vertical drop energy dissipation with horizontal serrated edge. Water Supply, 22(4), 4676-4689. https://doi.org/10.2166/ws.2022.127

Chamani, M. R., Rajaratnam, N., & Beirami, M. K. (2008). Turbulent jet energy dissipation at vertical drops. Journal of hydraulic engineering, 134(10), 1532-1535.
https://doi.org/10.1061/(ASCE)0733-9429(2008)134:10(1532)

Daneshfaraz, R., Hasanniya, V., Mirzaei, R., & Bazyar, A. (2020a). Experimental investigation of the effect of positive slope of the horizontal screen on hydraulic characteristics of vertical drop. Iranian Journal of Soil and Water Research, 50(10), 2499-2509. (In Persian).

Daneshfaraz, R., Majedi Asl, M., Razmi, S., Norouzi, R., & Abraham, J. (2020b). Experimental investigation of the effect of dual horizontal screens on the hydraulic performance of a vertical drop. International Journal of Environmental Science and Technology, 17, 2927-2936. https://doi.org/10.1007/s13762-019-02622-x

Esen, I. I., Alhumoud, J. M., & Hannan, K. A. (2004). Energy Loss at a Drop Structure with a Step at the Base. Water international, 29(4), 523-529. https://doi.org/10.1080/02508060408691816

Farouk, M., & Elgamal, M. (2012). Investigation of the performance of single and multi-drop hydraulic structures. International Journal of Hydrology Science and Technology, 2(1), 48-74.
https://doi.org/10.1504/IJHST.2012.045939

Ghaderi, A., Dasineh, M., & Abbasi, S. (2019). Impact of vertically constricted entrance on hydraulic characteristics of vertical drop (numerical investigation). Journal of Hydraulics, 13(4), 121-131.
https://doi.org/10.1007/s13201-019-1112-8

Blaisdell, F. W. (1980). HYDRAULICS OF RECTANGULAR VERTICAL DROP STRUCTURES: Journal of Hydraulic Research, Vol. 17, No. 4, 1979, pp. 289-302.

Hong, Y. M., Huang, H. S., & Wan, S. (2010). Drop characteristics of free-falling nappe for aerated straight-drop spillway. Journal of Hydraulic Research, 48(1), 125-129. https://doi.org/10.1080/00221680903568683

Kabiri-Samani, A. R., Bakhshian, E., & Chamani, M. R. (2017). Flow characteristics of grid drop-type dissipators. Flow measurement and instrumentation, 54, 298-306.
https://doi.org/10.1016/j.flowmeasinst.2016.11.002

Liu, S. I., Chen, J. Y., Hong, Y. M., Huang, H. S., & Raikar, R. V. (2014). Impact characteristics of free over-fall in pool zone with upstream bed slope. Journal of Marine Science and Technology, 22(4), 9.

Mansouri, R., & Ziaei, A. (2014). Numerical modeling of flow in the vertical drop with inverse apron.

Mirzaee, R., Hosseini, K., & Mousavi, F. (2021). Numerical investigation on energy loss in vertical drop with horizontal serrated edge. Journal of Hydraulics, 16(1), 23-36. (In Persian).

Rajaratnam, N., & Chamani, M. R. (1995). Energy loss at drops. Journal of Hydraulic Research, 33(3), 373-384. https://doi.org/10.1080/00221689509498578
Rand, W. (1955, September). Flow geometry at straight drop spillways. In Proceedings of the American Society of Civil Engineers (Vol. 81, No. 9, pp. 1-13). ASCE.

Sumer, B. M., & Fredsoe, J. (1991, August). Onset of scour below a pipeline exposed to waves. In ISOPE International Ocean and Polar Engineering Conference (pp. ISOPE-I). ISOPE.

Yonesi, H. A., Daneshfaraz, R., Mirzaee, R., & Bagherzadeh, M. (2023). Maximum energy loss in a vertical drop equipped with horizontal screen with downstream rough and smooth bed. Water Supply, 23(2), 960-974. https://doi.org/10.2166/ws.2023.005