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Homogeneous swarm of high-Reynolds-number bubbles rising within a thin gap. Part 2. Liquid dynamics

Bouche, Emmanuella and Roig, Véronique and Risso, Frédéric and Billet, Anne-Marie Homogeneous swarm of high-Reynolds-number bubbles rising within a thin gap. Part 2. Liquid dynamics. (2014) Journal of Fluid Mechanics, vol. 758. pp. 508-521. ISSN 0022-1120

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Official URL: http://dx.doi.org/10.1017/jfm.2014.544

Abstract

The agitation of the liquid phase has been investigated experimentally in a homogeneous swarm of bubbles rising at high Reynolds number within a thin gap. Owing to the wall friction, the bubble wakes are strongly attenuated. Consequently, liquid fluctuations result from disturbances localized near the bubbles and direct interactions between them. The signature of the average wake rapidly fades and the probability density function of the fluctuations becomes Gaussian as the gas volume fraction α increases. The energy of the fluctuations scales differently with α depending on the direction, indicating that hydrodynamic interactions are different in the horizontal and vertical directions. The spatial spectrum shows that the length scales of the fluctuations are independent of α and exhibits a k−3 subrange, which results from localized random flow disturbances of various sizes. Comparisons with the dynamics of the gas phase show that liquid and bubble agitations are driven by the same mechanism in the vertical direction, whereas they turn out to be almost uncoupled in the horizontal direction. Comparisons with unconfined flows show that the generation of liquid fluctuations is very different. However, the cause of the k−3 spectral subrange is the same for confined flows as for the spatial fluctuation of unconfined flows.

Item Type:Article
Additional Information:Thanks to Cambridge University Press. The definitive version is available at http://journals.cambridge.org The original PDF of the article can be found at Journal of Fluid Mechanics website : http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9377259&fileId=S0022112014005448
HAL Id:hal-01325329
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS (FRANCE)
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Deposited By: Frederic RISSO
Deposited On:02 Jun 2016 08:14

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