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Interaction of two axisymmetric bodies falling side by side at moderate Reynolds numbers

Ern, Patricia and Brosse, Nicolas Interaction of two axisymmetric bodies falling side by side at moderate Reynolds numbers. (2014) Journal of Fluid Mechanics, 741. ISSN 0022-1120

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Official URL: http://dx.doi.org/10.1017/jfm.2013.683

Abstract

We consider the interaction of two identical disks freely falling side by side in a fluid at rest for Reynolds numbers ranging from 100 to 300, corresponding to rectilinear and oscillatory paths. For the three aspect ratios of the disks investigated, we observed that the bodies always repel one another when the horizontal distance between their centres of gravity is less than 4.5 diameters. They never come closer for distances spanning between 4.5 and 6 diameters. Beyond the latter distance, the disks appear indifferent to each other. For both rectilinear and periodic paths, the repulsion effect is weak, leading to an overall horizontal drift lower than 3 % of the vertical displacement. We propose a model for the repulsion coefficient Cr, which decreases with the separation distance between the bodies and is inversely proportional to the aspect ratio of the bodies, Cr thus being stronger for the thicker ones. Furthermore, in the case of the oscillatory paths, we show that the effect of the interaction reduces to the repulsion effect, since the characteristics of the oscillatory motion of each disk appear unaffected by the presence of the companion disk and no synchronization is observed between the paths, nor between the wakes, of the two disks.

Item Type:Article
Additional Information:Thanks to Cambridge University Press editor. The definitive version is available at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9168342&fileId=S0022112013006836
HAL Id:hal-01017600
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 Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Patricia ERN
Deposited On:02 Jul 2014 16:01

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