Computational Study to Predict the Free-Surface Flow over Non-uniform Stepped Spillway Using ANSYS-CFX
DOI:
https://doi.org/10.25156/ptj.v10n1y2020.pp43-50Keywords:
Volume of fluid, Numerical simulation, Free-surface flow, Non-uniform stepped spillway, ANSYS-CFXAbstract
Using stepped chutes as a structure for controlling flood discharges is applicable for long time. Measuring the depth of flow over that structure is essential for designing of the side walls. The aim of this paper is to determine the free-surface that flows on spillway equipped with non-uniform step sizes. For that purpose, the two-dimensional software package code of ANSYS-CFX has been utilized to run eight configurations of two moderate slopes (1V:2H and 1V:2.5H) and for four different discharges 1≤dc/hs≤2.2 to determine the effect of flow discharges, chute slopes, and step heights on the position of free surface along the structure over non-uniform stepped cascade. The hexahedral grid size of 0.015 m is selected with inflation technique close to the walls. In addition, the renormalized group of k-ε (RNG) turbulence model is implemented and the numerical volume of fluid software is employed. The results show smoother stream for higher discharges, and the free-surface drops when the slope of chutes increases. Moreover, it is found that the step size has insignificant effect on the depth of water. The results of this study are important because they provide new insight in improving the design of stepped spillways. It is recommended to perform more investigations to evaluate their effectiveness in other flow parameters including pressure distribution and energy dissipation rates.
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Albadawi, A., D. Donoghue, A. Robinson, D. Murray and Y. Delauré. 2013. Influence of surface tension implementation in volume of fluid and coupled volume of fluid with level set methods for bubble growth and detachment. Int. J. Multiph. Flow. 53: 11-28.
André, S. and A. Schleiss. 2004. High Velocity Aerated Flows on Stepped Chutes with Macro-Roughness Elements. EPFL-LCH.
Bentalha, C. and M. Habi. 2019. Free surface profile and inception point as characteristics of aerated flow over stepped spillway: Numerical study. J. Water Land Dev. 42: 42-48.
Boes, R. M and W. H. Hager. 2003a. Hydraulic design of stepped spillways. J. Hydraul. Eng. 129: 671-679.
Boes, R. M. and W. H. Hager. 2003b. Two-phase flow characteristics of stepped spillways. J. Hydraul. Eng. 129: 661-670.
Bombardelli, F. A., I. Meireles and J. Matos. 2011. Laboratory measurements and multi-block numerical simulations of the mean flow and turbulence in the non-aerated skimming flow region of steep stepped spillways. Environ. Fluid Mech. 11: 263-288.
Chakib, B. and H. Mohammed. 2015. Numerical simulation of air entrainment for flat-sloped stepped spillway. J. Comput. Multiph. Flows. 7: 33-41.
Chamani, M. R. 1998. Skimming flow in a large model of a stepped spillway. Environ. Fluid Mech. 17(2): 303-322.
Chanson, H. 1994. Hydraulics of skimming flows over stepped channels and spillways. J. Hydraul. Res. 32: 445-460.
Chanson, H. 1996. Prediction of the transition nappe/skimming flow on a stepped channel. J. Hydraul. Res. 34: 421-429.
Chanson, H. 1998. Review of Studies on Stepped Channel Flows. Workshop on Flow Characteristics around Hydraulic Structures and River Environment, Nihon University, Tokyo, Japan.
Chanson, H. 2002. Hydraulics of Stepped Chutes and Spillways. CRC Press, Boca Raton, Florida.
Chinnarasri, C. and S. Wongwises. 2004. Flow regimes and energy loss on chutes with upward inclined steps. Can. J. Civil Eng. 31: 870-879.
Chow, V. T. 1959. Open-channel Hydraulics. McGraw-Hill Education, New York, New York.
Felder, S. 2013. Air-Water Flow Properties on Stepped Spillways for Embankment Dams: Aeration, Energy Dissipation and Turbulence on Uniform, Non-uniform and Pooled Stepped Chutes.
Gonzalez, C. A. 2005. An Experimental Study of Free-surface Aeration on Embankment Stepped Chutes. In: Presented as a Thesis to the University of Queensland for the degree of Doctor of Philosophy.
Husain, S. M. 2013. Computational Investigation of Skimming Flow on Stepped Spillways Using the Smoothed Particle Hydrodynamics Method. Swansea University, United Kingdom.
Husain, S. M., J. R. Muhammed, H. U. Karunarathna and D. E. Reeve. 2014. Investigation of pressure variations over stepped spillways using smooth particle hydrodynamics. Adv. Water
Resour. 66: 52-69.
Jalil, S. A. and B. S. Hussein. 2017. Experimental and modeling of flow over labyrinth and plain stepped falls. J. Duhok Univ. 20(1): 662-679.
Khalaf, R. M., R. H. Irzooki and S. J. Shareef. 2014. Flow characteristics and energy dissipation over traditional and stepped spillway with semicircular crest. Int. J. Civil Environ. Eng. 14(2): 13-27.
Li, S and J. Zhang. 2018. Numerical investigation on the hydraulic properties of the skimming flow over pooled stepped spillway. Water. 10: 1478.
Lucio, I. S. A. 2015. Numerical modeling of skimming flow over stepped spillways: Application on small embankment dams. Instituto Superior Tecnico, Lisbon .
Matos, J., M. Sanchez, A. Quintela and J. Dolz. 1999. Characteristic Depth and Pressure Profiles in Skimming Flow Over Stepped Spillways. Proceedings of the 29th IAHR Congress, Graz, Austria.
Saleh, S. M. and S. M. Husain. 2019. Validation of the computational ANSYS-CFX code for free surface flow: Skimming flow over non-uniform step size stepped spillways. ZANCO J. Pure Appl.
Sci. 31: 361-367.
Salim, S. M., S. Cheah and Y. Wall. Strategy for dealing with wallbounded turbulent flows. Proceedings of the international multiconference of engineers and computer scientists Conference: International Multi Conference of Engineers and Computer Scientists, IMECS 2009.
Tabbara, M., J. Chatila and R. Awwad. 2005. Computational simulation of flow over stepped spillways. Comput. Struct. 83: 2215-2224.
Team, L. C. 2013. Tips and tricks: Estimating the first cell height for correct Y+. Leap Australia Computational Fluid Dynamics Blog (CFD). Available from: https://www.computationalfluiddynamics. com.au/tips-tricks-cfd-estimate-first-cell-height. [Last accessed on 2013 Jul 01].
Turan, C., M. Politano, P. Carrica and L. Weber. 2007. Water entrainment due to spillway surface jets. Int. J. Comput. Fluid Dyn. 21: 137-153.
Valero, D. and D. B. Bung, D. B. 2015. Hybrid Investigations of Air Transport Processes in Moderately Sloped Stepped Spillway Flows. E-Proceedings of the 36th IAHR World Congress.
Van Alwon, J., D. Borman, A. Sleigh and N. Kapur. 2017. Experimental and Numerical Modelling of Aerated Flows Over Stepped Spillways. Proceedings of IAHR 2017 International Association for Hydro-Environment Engineering and Research.
Witt, A., J. Gulliver and L. Shen. 2015. Simulating air entrainment and vortex dynamics in a hydraulic jump. Int. J. Multiph. Flow. 72: 165-180.
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