An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes

Gonzalez, Carlos A., Takahashi, Masayuki and Chanson, Hubert (2008) An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes. Journal of Hydraulic Research, 46 S1: 24-35. doi:10.1111/j.1365-2222.2008.02941.x

Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
jhr08_s1.pdf jhr08_s1.pdf application/pdf 1.10MB 721

Author Gonzalez, Carlos A.
Takahashi, Masayuki
Chanson, Hubert
Title An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes
Journal name Journal of Hydraulic Research   Check publisher's open access policy
ISSN 0022-1686
Publication date 2008
Year available 2008
Sub-type Article (original research)
DOI 10.1111/j.1365-2222.2008.02941.x
Open Access Status File (Author Post-print)
Volume 46
Issue S1
Start page 24
End page 35
Total pages 12
Publisher IAHR
Collection year 2008
Language eng
Subject 290000 Engineering and Technology
290800 Civil Engineering
290802 Water and Sanitary Engineering
291803 Turbulent Flows
Abstract On a spillway chute, a stepped design increases the rate of energy dissipation on the chute itself and reduces the size of a downstream energy dissipator. Up to date, the effects of step roughness on the flow properties remain unknown despite the practical relevance to damaged concrete steps, rock chutes and gabions weirs. New measurements were conducted in a large-size laboratory facility with two step conditions (smooth and rough) and three types of step roughness. Detailed air-water flow properties were measured systematically for several flow rates. The results showed faster flow motion on rough step chutes. Although the finding is counter-intuitive, it is linked with the location of the inception point of free-surface aeration being located further downstream than for a smooth stepped chute for an identical flow rate. In the aerated flow region, the velocities on rough-step chutes were larger than those of smooth chute flows for a given flow rate and dimensionless location from the inception point of free-surface aeration both at step edges and between step edges. The results suggest that design guidelines for smooth (concrete) stepped spillway may not be suitable to rough stepped chutes including gabion stepped weirs, and older stepped chutes with damaged steps.
Keyword Stepped spillway
Skimming flow
Step roughness
Air-water flow
Physical modelling
Flow resistance
Form drag
Energy dissipation
Gabion stepped weir
Damaged concrete steps
References ANDRE, S., BOILLAT, J.L., SCHLEISS, A.J., and MATOS, J. (2004). "Energy Dissipation and Hydrodynamic Forces of Aerated Flow over Macro-Roughness Linings for Overtopped Embankment Dams." Proc. Intl Conf. on Hydraulics of Dams and River Structures, Tehran, Iran, Balkema Publ., The Netherlands, pp. 189-196. BaCaRa (1991). "Etude de la Dissipation d'Energie sur les Evacuateurs à Marches." Rapport d'Essais, Projet National BaCaRa, CEMAGREF-SCP, Aix-en-Provence, France, Oct., 111 pages. BOES, R.M. (2000). "Scale Effects in Modelling Two-Phase Stepped Spillway Flow." Intl Workshop on Hydraulics of Stepped Spillways, Zürich, Switzerland, Balkema Publ., pp. 53-60. CHANSON, H. (1995). "Hydraulic Design of Stepped Cascades, Channels, Weirs and Spillways." Pergamon, Oxford, UK, Jan., 292 pages. CHANSON, H. (1997). "Air Bubble Entrainment in Free-Surface Turbulent Shear Flows." Academic Press, London, UK, 401 pages. CHANSON, H. (2001). "The Hydraulics of Stepped Chutes and Spillways." Balkema, Lisse, The Netherlands, 418 pages. CHANSON, H. (2004). "The Hydraulics of Open Channel Flows : An Introduction." Butterworth-Heinemann, Oxford, UK, 2nd edition, 630 pages. CHANSON, H., and GONZALEZ, C.A. (2004). "Interactions between Free-surface, Free-stream Turbulence and Cavity Recirculation in Open Channel Flows: Measurements and Turbulence Manipulation." Proc. 5th Intl Conf. on Multiphase Flow, Yokohama, Japan, Y. MATSUMOTO, K. HISHIDA, A. TOMIYAMA, K. MISHIMA and S. HOSOKAWA editors, Paper 104, 14 pages (CD-ROM). CHANSON, H., and GONZALEZ, C.A. (2005). "Physical Modelling and Scale Effects of Air-Water Flows on Stepped Spillways." Journal of Zhejiang University SCIENCE, Vol. 6A, No. 3, March, pp. 243-250. CHANSON, H., and TOOMBES, L. (2001). "Experimental Investigations of Air Entrainment in Transition and Skimming Flows down a Stepped Chute. Application to Embankment Overflow Stepped Spillways." Research Report No. CE158, Dept. of Civil Engineering, The University of Queensland, Brisbane, Australia, July, 74 pages. CHANSON, H., and TOOMBES, L. (2002). "Air-Water Flows down Stepped chutes : Turbulence and Flow Structure Observations." Intl Jl of Multiphase Flow, Vol. 28, No. 11, pp. 1737-1761. CHANSON, H., and TOOMBES, L. (2003). "Strong Interactions between Free-Surface Aeration and Turbulence in an Open Channel Flow." Experimental Thermal and Fluid Science, Vol. 27, No. 5, pp. 525-535. CHANSON, H., YASUDA, Y., and OHTSU, I. (2002). "Flow Resistance in Skimming Flows and its Modelling." Can Jl of Civ. Eng., Vol. 29, No. 6, pp. 809-819. GONZALEZ, C.A. (2005). "An Experimental Study of Free-Surface Aeration on Embankment Stepped Chutes." Ph.D. thesis, Department of Civil Engineering, The University of Queensland, Brisbane, Australia. GONZALEZ, C., and CHANSON, H. (2004a). "Effects of Turbulence Manipulation in Skimming Flows: An Experimental Study." Proc. 15th Australasian Fluid Mech. Conf., AFMC, Sydney, Australia, M. BEHNIA, W. LIN & G.D. McBAIN Ed., Paper AFMC00104, 4 pages (CD-ROM). GONZALEZ, C.A., and CHANSON, H. (2004b). "Interactions between Cavity Flow and Main Stream Skimming Flows: an Experimental Study." Can Jl of Civ. Eng., Vol. 31, No. 1, pp. 33-44. GONZALEZ, C.A., TAKAHASHI, M., and CHANSON, H. (2005). "Effects of Step Roughness in Skimming Flows: an Experimental Study." Research Report No. CE160, Dept. of Civil Engineering, The University of Queensland, Brisbane, Australia, July, 149 pages. HENDERSON, F.M. (1966). "Open Channel Flow." MacMillan Company, New York, USA. HOMSY, G.M. (2000). "Multi-Media Fluid Mechanics." Cambridge University Press, Cambridge, UK, CD-ROM. KELLS, J.A. (1993). "Spatially Varied Flow over Rockfill Embankments." Can. Jl of Civ. Engrg., Vol. 20, pp. 820-827. Discussion : Vol. 21, No. 1, pp. 161-166. KELLS, J.A. (1995). "Comparison of Energy Dissipation between Nappe and Skimming Flow Regimes on Stepped Chutes - Discussion." Jl of Hyd. Res., IAHR, Vol. 33, No. 1, pp. 128-133. KOKPINAR, M.A. (2005). "Flow over a Stepped Chute with and without Macro-Roughness Elements." Can. Jl of Civil Eng., Vol.. 31, No. 5, pp. 880-891. NAUDASCHER, E., and ROCKWELL, D. (1994). "Flow-Induced Vibrations. An Engineering Guide." IAHR Hydraulic Structures Design Manual No. 7, Hydraulic Design Considerations, Balkema Publ., Rotterdam, The Netherlands, 413 pages. OHTSU, I., YASUDA, Y., and TAKAHASHI, M. (2004). "Flow Characteristics of Skimming Flows in Stepped Channels." Jl of Hyd. Engrg., ASCE, Vol. 130, No. 9, pp. 860-869. PEYRAS, L., ROYET, P., and DEGOUTTE, G. (1991). "Ecoulement et Dissipation sur les Déversoirs en Gradins de Gabions." Jl La Houille Blanche, No. 1, pp. 37-47. RAJARATNAM, N. (1990). "Skimming Flow in Stepped Spillways." Jl of Hyd. Engrg., ASCE, Vol. 116, No. 4, pp. 587-591. Discussion : Vol. 118, No. 1, pp. 111-114. WOOD, C.J. (1964). "The Effect of Base Bleed on periodic Wake." Jl Roy. Aeronautical Soc., Vol. 68, pp. 477-482. WOOD, I.R., ACKERS, P., and LOVELESS, J. (1983). "General Method for Critical Point on Spillways." Jl. of Hyd. Eng., ASCE, Vol. 109, No. 2, pp. 308-312. YASUDA, Y., and CHANSON, H. (2003). "Micro- and Macro-scopic Study of Two-Phase Flow on a Stepped Chute." Proc. 30th IAHR Biennial Congress, Thessaloniki, Greece, J. GANOULIS and P. PRINOS Ed., Vol. D, pp. 695-702.
Q-Index Code C1
Q-Index Status Provisional Code
Additional Notes The full bibliographic details are : GONZALEZ, C.A., TAKAHASHI, M., and CHANSON, H. (2008). "An Experimental Study of Effects of Step Roughness in Skimming Flows on Stepped Chutes." Journal of Hydraulic Research, IAHR, Vol. 46, No. Extra Issue 1, pp. 24-35 (ISSN 0022-1686).

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Civil Engineering Publications
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 15 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 0 times in Scopus Article
Google Scholar Search Google Scholar
Created: Thu, 17 Apr 2008, 15:17:04 EST by Hubert Chanson on behalf of School of Civil Engineering