Turbulence and Cavity Recirculation in Air-Water Skimming Flows on a Stepped Spillway. Reply

Gonzalez, Carlos A. and Chanson, Hubert (2009) Turbulence and Cavity Recirculation in Air-Water Skimming Flows on a Stepped Spillway. Reply. Journal of Hydraulic Research, 47 2: 283-284.

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Author Gonzalez, Carlos A.
Chanson, Hubert
Title Turbulence and Cavity Recirculation in Air-Water Skimming Flows on a Stepped Spillway. Reply
Journal name Journal of Hydraulic Research   Check publisher's open access policy
ISSN 0022-1686
Publication date 2009
Year available 2009
Sub-type Editorial
Open Access Status File (Author Post-print)
Volume 47
Issue 2
Start page 283
End page 284
Total pages 2
Collection year 2009
Language eng
Subject 09 Engineering
0905 Civil Engineering
090509 Water Resources Engineering
CX
Abstract The authors acknowledge the discussion. In the present study, 1.6mm thick aluminum triangular vanes were used, although a number of 6mm thick perspex vanes were also tested. The experimental observations showed no effect of vane thickness on the flow patterns and properties. They did not support the Discussers’ argument. The authors however disagree with the Discusser’s comment on the rate of energy dissipation on stepped spillways and a so-called "most efficient solution" for practical applications. In terms of energy dissipation, the current expertise is restricted to rectangular, prismatic stepped chutes with horizontal steps, constant step height and constant bed slope, as shown in most earlier studies. Recently, detailed air-water flow results on stepped chutes showed systematically lower turbulence levels and larger turbulent length and time scales in comparison between 2:1 Froude similar experiments in laboratory flumes, as well as a smaller number of entrained bubbles and comparatively larger bubble sizes (Chanson and Gonzalez 2005, Chanson 2008). These findings have direct implications on the design of stepped spillway because reduced turbulence levels in laboratory flumes must imply a reduced rate of turbulent dissipation, particularly on long channels. Simply small-size models are likely to underestimate the rate of energy dissipation of prototype stepped spillways for similar flow conditions. The current understanding of energy dissipation on stepped spillway is clearly incomplete and the concept of the most efficient design is therefore an utopia.
Keyword stepped spillways
Energy dissipation
Turbulence
Q-Index Code CX
Additional Notes The full bibliographic details are: GONZALEZ, C.A., and CHANSON, H. (2009). "Turbulence and Cavity Recirculation in Air-Water Skimming Flows on a Stepped Spillway. Reply." Journal of Hydraulic Research, IAHR, Vol. 47, No. 2, pp. 283-284 (ISSN 0022-1686).

Document type: Journal Article
Sub-type: Editorial
Collection: School of Civil Engineering Publications
 
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Created: Wed, 15 Apr 2009, 07:13:55 EST by Hubert Chanson on behalf of School of Civil Engineering