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Numerical investigation of flow field characteristics over vertical drops with sudden contraction for different contraction ratios | ||
| Journal of Applied Research in Water and Wastewater | ||
| دوره 12، شماره 1 - شماره پیاپی 23، شهریور 2025، صفحه 58-63 اصل مقاله (1.16 M) | ||
| نوع مقاله: Research Paper | ||
| شناسه دیجیتال (DOI): 10.22126/arww.2025.11775.1356 | ||
| نویسندگان | ||
| Hossein Shahin؛ Afshin Eghbalzadeh* ؛ Mitra Javan | ||
| Department of Civil Engineering, Faculty of Engineering, Razi University, Kermanshah, Iran. | ||
| چکیده | ||
| Vertical drops are widely implemented in hydraulic structures such as irrigation canals, wastewater collection systems, and stepped spillways to dissipate flow kinetic energy while enhancing aeration and promoting dissolved oxygen levels. Depending on local topography, these structures serve to reduce the kinetic energy of falling water and to regulate the flow velocity within canals and irrigation networks. In this study, a three-dimensional numerical simulation was performed to investigate the flow pattern over a vertical drop featuring a sudden contraction under various contraction ratios. The simulation employed the RNG k-ε turbulence model in conjunction with the volume of fluid (VOF) method to capture free surface dynamics. The computational model was validated against experimental data, yielding acceptable levels of accuracy based on average percentage error (APE) and root mean square error (RMSE) metrics. Moreover, results indicate that a reduction in the contraction ratio leads to an increase in the falling jet thickness and hydraulic jump height, accompanied by a decrease in the water jet length. These changes promote enhanced energy dissipation, which is critical for reducing the kinetic energy of the flow in hydraulic structures such as irrigation canals, wastewater collection systems, and spillways. The findings suggest that optimizing the contraction ratio is an effective design parameter for improving energy dissipation efficiency and overall hydraulic performance. | ||
| کلیدواژه‌ها | ||
| Vertical drop؛ Contraction ratio؛ Falling jet؛ Free surface؛ Sudden contraction | ||
| مراجع | ||
|
Ajeel Fenjan, S., Akhtari, A.A. and Gholami, A. (2022) 'Determination of discharge coefficient in the tilted crown sharp-crested weirs', Journal of Applied Research in Water and Wastewater, 9(2), pp. 180–186. doi: https://doi.org/10.22126/arww.2022.2538.1216
Bakhmeteff, B. (1932) Hydraulics of open channels. 1th edn. New York: McGraw-Hill.
Chamani, M.R. and Beirami, M.K. (2002) ‘Flow characteristic at drops’, Journal of Hydraulic Engineering, 128(8), pp. 788–791. doi: https://doi.org/10.1061/(ASCE)0733-9429(2002)128:8(788)
Chamani, M.R., Rajaratnam, N. and Beirami, M.K. (2008) ‘Turbulent jet energy dissipation at vertical drops’, Journal of Hydraulic Engineering, 134(10), pp. 1532–1535. doi: https://doi.org/10.1061/(ASCE)0733-9429(2008)134:10(1532)
Chanson, H. (1994) ‘Comparison of energy dissipation between nappe and skimming flow regimes on stepped chutes’, Journal of Hydraulic Research, 32(2), pp. 213–218. doi: https://doi.org/10.1016/0022-1694(94)90024-3
Fereshtepour, M. et al. (2012) ‘Three-dimensional simulation of the flow over vertical drop with convergent and divergent transitions using OpenFOAM software’, Proceedings of the 11th Iranian Hydraulic Conference. Urmia, Iran, 6-8 Nov. Urmia: University of Urmia, pp. 1-7.
Gill, M.A. (1979) ‘Hydraulics of rectangular vertical drop structures’, Journal of Hydraulic Research, 17(4), pp. 289–302. doi: https://doi.org/10.1016/0022-1694(79)90010-8
Hager, W.H. (1983) ‘Hydraulic stresses on an overfall’, Journal of Hydraulic Engineering, 109(12), pp. 1683–1697. doi: https://doi.org/10.1061/(ASCE)0733-9429(1983)109:12(1683)
Hirt, C. and Nichols, B. (1981) ‘Volume of fluid (VOF) method for the dynamics of free boundaries’, Journal of Computational Physics, 39, pp. 201–225. doi: https://doi.org/10.1016/0021-9991(81)90052-4
Janfeshan Araqi, H. and Lashkar Bolook, H. (2013) ‘Presenting a criterion for predicting the flow pattern over a vertical drop based on its hydraulic and geometric characteristics’, Proceedings of the 12th Iranian Hydraulic Conference. Tehran, Iran, 29-31 Oct. Tehran: University of Tehran, pp.1-8.
Jannati, H. (2009) Vertical drop with a contraction transition and subcritical flow upstream. MS Dissertation. Isfahan University of Technology.
Kohzadi, A., Mohammadi, K. and Eghbalzadeh, A. (2024) ‘Application of various methods in design for control of bed erosion and river modification aiding numerical simulation’, Journal of Applied Research in Water and Wastewater, 11(2), pp. 151–161. doi: https://doi.org/10.22126/arww.2025.10877.1338
Mansouri, R. and Ziaee, A.N. (2011) ‘Two-dimensional numerical simulation of flow pattern in vertical drop considering different boundary situations’, Proceedings of the 6th National Congress on Civil Engineering. Semnan, Iran, 26-27 Apr. Semnan: Semnan University, pp. 1-7.
Ming Hong, Y., Shin Huang, H. and Wan, S. (2010) ‘Drop characteristics of free-falling nappe for aerated straight-drop spillway’, Journal of Hydraulic Research, 48(1), pp. 125–129. doi: https://doi.org/10.1016/j.jhydro.2009.12.001
Moore, W.L. (1943) ‘Energy loss at the base of free overfall’, Transactions of the American Society of Civil Engineers, 108, pp. 1343–1360. doi: https://doi.org/10.1061/(ASCE)0733-9429(1943)108:1343
Othman Ahmed, K. et al. (2021) 'Numerical modeling of depth and location of scour at culvert outlets under unsteady flow conditions', Journal of Pipeline Systems Engineering and Practice, 12(4), p. 4021040. doi: https://doi.org/10.1061/(ASCE)PS.1949-1204.0000578
Othman Ahmed, K. et al. (2024) 'Numerical modelling of downstream scour in circular culverts: Impact of inlet blockages and variable flow conditions', Plos One, pp. 1–25. doi: https://doi.org/10.1371/journal.pone.0312501
Rajaratnam, N. and Chamani, M.R. (1995) ‘Energy loss at drops’, Journal of Hydraulic Research, 33(3), pp. 373–384. doi: https://doi.org/10.1061/(ASCE)0733-9429(1995)33:3(373)
Rajaratnam, N. and Wu, S. (1998) ‘Impinging jet and surface flow regimes at drops’, Journal of Hydraulic Research, 36(1), pp. 69–74. doi: https://doi.org/10.1061/(ASCE)0733-9429(1998)36:1(69)
Rand, W. (1955) ‘Flow geometry at straight drop spillways’, Proceedings of the American Society of Civil Engineers, 81, pp. 1–13. doi: https://doi.org/10.1061/(ASCE)0733-9429(1955)81:1(1)
Razmi, M., Saneie, M. and Basirat, S. (2022) 'Comparative evaluation of CFD model and intelligence hybrid method to ameliorate ANFIS in side weir coefficient of discharge modelling', Journal of Applied Research in Water and Wastewater, 9(2), pp. 125–140. doi: https://doi.org/10.22126/arww.2023.7934.1255
Sicilian, J.M., Hirt, C.W. and Harper, R.P. (1987) FLOW-3D. Computational Modeling Power for Scientists and Engineers. Report FSI-87-00-1. Flow Science, Los Alamos.
Tsai, C.P., Yen, C.C. and Lin, C. (2014) ‘Simulations on skimming flow over a vertical drop pool’, Journal of Engineering Mechanics, 140(7), 04014044. doi: https://doi.org/10.1061/(ASCE)0733-9429(2014)140:7(04014044)
Versteeg, H.K. and Malalasekera, W. (2007) An introduction to computational fluid dynamics: The finite volume method. 2nd edn. London: Pearson Education. | ||
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