Unsteady turbulence in a shock: physical and numerical modelling in tidal bores and hydraulic jumps

Chanson, Hubert, Lubin, Pierre and Glockner, Stephane (2012). Unsteady turbulence in a shock: physical and numerical modelling in tidal bores and hydraulic jumps. In Russell J. Marcuso (Ed.), Turbulence: theory, types and simulation (pp. 113-148) Hauppauge NY, USA: Nova Science Publishers.

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Author Chanson, Hubert
Lubin, Pierre
Glockner, Stephane
Title of chapter Unsteady turbulence in a shock: physical and numerical modelling in tidal bores and hydraulic jumps
Title of book Turbulence: theory, types and simulation
Place of Publication Hauppauge NY, USA
Publisher Nova Science Publishers
Publication Year 2012
Sub-type Research book chapter (original research)
Open Access Status
Series Physics Research and Technology
ISBN 9781617617355
1617617350
Editor Russell J. Marcuso
Chapter number 3
Start page 113
End page 148
Total pages 36
Total chapters 15
Collection year 2013
Language eng
Abstract/Summary A turbulent flow is characterised by an unpredictable behaviour, a broad spectrum of length and time scales, and its strong mixing properties. Turbulent flows have a great mixing potential involving a wide range of vortical length scales. In steady flows, the turbulence measurements must be conducted at high frequency to resolve the small eddies and the viscous dissipation process. They must also be performed over a period significantly larger than the characteristic time of the largest vortical structures. In a highly unsteady flow, such as a shock, the experimental technique must be adapted, and this is detailed herein for positive surges, tidal bores and hydraulic jumps. A review of detailed turbulence measurements in tidal bores is conducted, and a number of laboratory experimental techniques are compared together with two- and three-dimensional large eddy simulation (LES) calculations. The experimental results demonstrate that the propagation of tidal bores induces some substantial turbulent mixing in natural estuaries. The passage of a tidal bore is associated with some large water depth fluctuations. Both the instantaneous and ensemble-averaged turbulent velocity data highlight some seminal features of the flow field in tidal bores. The instantaneous velocity measurements and the numerical data show a marked effect of the tidal bore front passage. The streamwise velocities are always characterised by a rapid flow deceleration at all vertical elevations, and large fluctuations of all velocity components are recorded beneath the surge and whelps. Both physical and numerical studies document the production of large coherent structures in tidal bores. The existence of such energetic turbulent events beneath and shortly after the tidal bore front implies the generation of vorticity during the bore propagation. Some experimental results show further that the variable interval time averaged (VITA) data based upon a single run present some non-negligible differences with the ensemble-averaged (EA) median results in terms of all velocity components. Both the EA and VITA methods showed some comparable long-term trends superposed to some rapid turbulent fluctuations, as well as close results in terms of the turbulent Reynolds stress components.
Keyword Hydraulic jumps
Tidal bores
Turbulence
Unsteady flow
Shock
Physical modelling
Numerical modelling
Large eddy simulation LES
Ensemble average
Variable interval time average VITA
Q-Index Code B1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes The full bibliographic details are: CHANSON, H., LUBIN, P., and GLOCKNER, S. (2012). "Unsteady Turbulence in a Shock: Physical and Numerical Modelling in Tidal Bores and Hydraulic Jumps." in "Turbulence: Theory, Types and Simulation", Nova Science Publishers, Hauppauge NY, USA, Ed. R.J. MARCUSO, Chapter 3, pp. 113-148 (ISBN 978-1-61761-735-5).

Document type: Book Chapter
Collections: School of Civil Engineering Publications
Official 2013 Collection
 
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Created: Mon, 26 Mar 2012, 11:36:16 EST by Hubert Chanson on behalf of School of Civil Engineering