Numerical Study to Evaluate the Performance of Nonuniform Stepped Spillway Using ANSYS-CFX




ANSYS-CFX, Energy dissipation, Inception point, Non-uniform stepped spillway, Numerical simulation


The main features that attract hydraulic engineers for designing stepped spillways are their ability to lose a large portion of the flow energy and add or increase aeration to the flow naturally. Hence, smaller size stilling basin and no aeration device may require. This study aims to find the amount of energy dissipation rate and the location of inception point over non-uniform stepped spillway. The numerical 2D ANSYS-CFX code is applied to generate and run thirty-two models of different configurations using two different moderate slopes (1 V:2 H and 1 V:2.5 H) as most of the downstream slopes designed for moderate slope, and two different step heights (hs= 0.08 m and hs= 0.016 m) under skimming flow discharge for different (dc/hs) ranging from dc/hs= 1–2.2, in which dc is the critical flow deptho n the crest. The volume of fluid is implemented and the renormalized group of k-ɛ turbulence model is activated. The computational results demonstrated that the amount of energy dissipation increases with decreasing the flow discharge, chute slope, and step height. In addition, it is observed that the length of the inception point is directly proportional to the discharge and inversely proportional to both the chute slopes and step height. Moreover, for the design point of view, the results revealed that configuration B can be considered as the optimal one amongst the others examined herein.


Download data is not yet available.


Ahadian, J. and R. Aghamajidi. 2014. Investigation of geometric effect of steps on energy dissipation on stepped spillway. Appl. Math. Eng. Manag. Technol. 2: 491-503.

Arora, C. 2017. Analysis of flow over a stepped spillway using ansys fluent. Imperial J. Interdiscip. Res. 3: 297-302.

Attarian, A., K. Hosseini, H. Abdi and M. Hosseini. 2014. The effect of the step height on energy dissipation in stepped spillways using numerical simulation. Arab. J. Sci. Eng. 39: 2587-2594.

Boes, R. M. and W. H. Hager. 2003. Two-phase flow characteristics of stepped spillways. J. Hydraul. Eng. 129: 661-670.

Chafi, C., A. Hazzab and A. Seddini. 2010. Study of flow and energy dissipation in stepped spillways. Jordan J. Civil Eng. 4: 1-11.

Chamani, M. R. 1998. Skimming flow in a large model of a stepped spillway. J. Hydraul. Eng. 135: 47.

Chanson, H. 1994. Hydraulics of skimming flows over stepped channels and spillways. J. Hydraul. Res. 32: 445-460.

Chanson, H. 2002. Hydraulics of Stepped Chutes and Spillways. CRC Press, Boca Raton, Florida, United States.

Chinnarasri, C. and S. Wongwises. 2004. Flow regimes and energy loss on chutes with upward inclined steps. Can. J. Civil Eng. 31: 870-879.

Chinnarasri, C., D. Kositgittiwong and P. Y. Julien. 2014. Model of Flow Over Spillways by Computational Fluid Dynamics. In: Proceedings of the Institution of Civil Engineers-Water Management. Thomas Telford Ltd., London, England. p164-175.

Chow, V. T. 1959. Open-Channel Hydraulics. McGrow-Hill, New York. Christodoulou, G. C. 1993. Energy dissipation on stepped spillways. J. Hydraul. Eng. 119: 644-650.

Degoutte, G., L. Peyras and P. Royet. 1992. Discussion of “skimming flow in stepped spillways” by N. Rajaratnam (April, 1990, Vol. 116, No. 4). J. Hydraul. Eng. 118: 111-113.

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. Phd. Thesis.

Felder, S. and H. Chanson. 2009. Turbulence, dynamic similarity and scale effects in high-velocity free-surface flows above a stepped chute. Exp. Fluids. 47: 1-18.

Guenther, P., S. Felder and H. Chanson. 2013. Flow aeration, cavity processes and energy dissipation on flat and pooled stepped spillways for embankments. Environ. Fluid Mech. 13: 503-525.

Hamedi, A., I. Malekmohammadi, A. Mansoori and H. Roshanaei. 2012. Energy Dissipation in Stepped Spillway Equipped with Inclined Steps Together with End Sill. In: 4th International Conference on Computational Intelligence and Communication Networks. IEEE, Piscataway, New Jersey. p638-642.

Hunt, S. L. and K. C. Kadavy. 2009. Inception Point Relationship for Flat-sloped Stepped Spillways, 2009 Reno, Nevada, June 21- June 24, 2009. American Society of Agricultural and Biological Engineers, St. Joseph, Michigan, United States.

Hunt, S. L. and K. C. Kadavy. 2010. Energy dissipation on flat-sloped stepped spillways: Part 1. Upstream of the inception point. Trans. ASABE. 53: 103-109.

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. and S. S. Ahmed. 2017. Experimental study to evaluate the hydraulic performance of Bastora dam stepped spillway. J. Duhok Univ. 20: 612-625.

Jalil, S. A. and B. S. Hussein. 2017. Experimental and modelling of flow over labyrinth and plain stepped falls. J. Duhok Univ. 10: 662-679.

Kavianpour, M. R. and H. R. Masoumi. 2008. New approach for estimating of energy dissipation over stepped spillways. Int. J. Civil Eng. 6: 230-237.

Khalaf, R. M., R. H. Irzooki and S. J. Shareef. 2014. Flow Characteristics and Energy Dissipation Over Traditional and Stepped Spillway with Semicircular Crest, Project.

Li, S. and J. Zhang. 2018. Numerical investigation on the hydraulic properties of the skimming flow over pooled stepped spillway. Water. 10: 1478.

Munta, S. and J. Otun. 2014. Study of the inception length of flow over stepped spillway models. Niger. J. Technol. 33: 176-183.

Rad, I. N. and M. Teimouri. 2010. An investigation of flow energy dissipation in simple stepped spillways by numerical model. Eur. J. Sci. Res. 47: 544-553.

Rajaratnam, N. 1990. Skimming flow in stepped spillways. J. Hydraul. Eng. 116: 587-591.

Rice, C. E. and K. C. Kadavy. 1996. Model study of a roller compacted concrete stepped spillway. J. Hydraul. Eng. 122: 292-297.

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.

Tabbara, M., J. Chatila and R. Awwad. 2005. Computational simulation of flow over stepped spillways. Comput. Struct. 83: 2215-2224.

Tatewar, S. P. and R. N. Ingle. 1996. Energy dissipation in skimming flow over stepped spillways. ISH J. Hydraul. Eng. 2: 45-51.

Van Alwon, J., D. Borman, A. Sleigh and N. Kapur. 2017. Experimental and Numerical Modelling of Aerated Flows Over Stepped Spillways. In: Proceedings of IAHR 2017. International Association for Hydro-Environment Engineering and Research.

Zhang, G. and H. Chanson. 2016. Hydraulics of the developing flow region of stepped spillways. I: Physical modeling and boundary layer development. J. Hydraul. Eng. 142: 04016015.



How to Cite

Saleh, S. M., & Husain, S. M. (2020). Numerical Study to Evaluate the Performance of Nonuniform Stepped Spillway Using ANSYS-CFX. Polytechnic Journal, 10(2), 1-9.



Research Articles