Energy dissipation, flow resistance and gas-liquid interfacial area in skimming flows on moderate-slope stepped spillways

Felder, Stefan and Chanson, Hubert (2009) Energy dissipation, flow resistance and gas-liquid interfacial area in skimming flows on moderate-slope stepped spillways. Environmental Fluid Mechanics, 9 4: 427-441. doi:10.1007/s10652-009-9130-y

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Author Felder, Stefan
Chanson, Hubert
Title Energy dissipation, flow resistance and gas-liquid interfacial area in skimming flows on moderate-slope stepped spillways
Journal name Environmental Fluid Mechanics   Check publisher's open access policy
ISSN 1567-7419
1573-1510
Publication date 2009-08
Year available 2009
Sub-type Article (original research)
DOI 10.1007/s10652-009-9130-y
Open Access Status File (Author Post-print)
Volume 9
Issue 4
Start page 427
End page 441
Total pages 15
Editor Benoit Cushman-Roisin
Place of publication Dordrecht, Netherlands
Publisher Springer Netherlands
Collection year 2010
Language eng
Subject 090509 Water Resources Engineering
C1
970109 Expanding Knowledge in Engineering
Abstract With the re-evaluation and revision of a number of design floods, several embankment overtopping protection systems have been developed and a common technique is the construction of a stepped spillway on the downstream slope. For such moderate slope stepped channels, detailed air–water flowmeasurements were performed in a large facility with a focus on the rate of energy dissipation, flow resistance, air–water interfacial areas and re-aeration rates. Past and present experimental results showed a significant aeration of the flow. The median dimensionless residual head was about 3×dc for the 21.8◦ sloping chute and smaller than that for flatter slopes (θ = 3.4 and 15.9 degrees). The flow resistance results yielded an equivalent Darcy friction factor of about 0.25 implying a larger flow resistance for the 21.8 degree slope angle than for smaller slope angles. The re-aeration rate was deduced from the integration of the mass transfer equation using measured air–water interfacial areas and air–water flow velocities. The results suggested an increasing re-aeration rate with increasing rate of energy dissipation. The stepped invert contributed to intense turbulence production, free-surface aeration and large interfacial areas. The experimental data showed however some distinctive seesaw pattern in the longitudinal distribution of air–water flow properties with a wave length of about two step cavities. While these may be caused by the interactions between successive adjacent step cavities and their interference with the free-surface, the existence of such "instabilities" implies that the traditional concept of normal flow might not exist in skimming flows above moderate-slope stepped spillways.
Keyword Stepped spillways
Aeration
Energy Dissipation
Flow resistance
Re-oxygenation
Water quality
Q-Index Code C1
Q-Index Status Confirmed Code
Additional Notes The full bibliographic details are: FELDER, S., and CHANSON, H. (2009). "Energy Dissipation, Flow Resistance and Gas-Liquid Interfacial Area in Skimming Flows on Moderate-Slope Stepped Spillways." Environmental Fluid Mechanics, Vol. 9, No. 4, pp. 427-441 (DOI: 10.1007/s10652-009-9130-y) (ISSN 1567-7419 [Print] 1573-1510 [Online]).

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Civil Engineering Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 19 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 25 Jun 2009, 10:55:57 EST by Hubert Chanson on behalf of School of Civil Engineering