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Path oscillations and enhanced drag of light rising spheres

Auguste, Franck and Magnaudet, Jacques Path oscillations and enhanced drag of light rising spheres. (2018) Journal of Fluid Mechanics, 841. 228-266. ISSN 0022-1120

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Official URL: https://doi.org/10.1017/jfm.2018.100

Abstract

The dynamics of light spheres rising freely under buoyancy in a large expanse of viscous fluid at rest at infinity is investigated numerically. For this purpose, the computational approach developed by Mougin \& Magnaudet (Int. J. Multiphase Flow, 28:1837-1851, 2002) is improved to account for the instantaneous viscous loads induced by the translational and rotational sphere accelerations, which play a crucial role in the dynamics of very light spheres. A comprehensive map of the rise regimes encountered up to Reynolds numbers (based on the sphere diameter and mean rise velocity) of the order of $10^3$ is set up by varying independently the body-to-fluid density ratio and the relative magnitude of inertial and viscous effects in about $250$ distinct combinations. These computations confirm or reveal the presence of several distinct periodic regions on the route to chaos, most of which only exist within a finite range of the sphere relative density and Reynolds number. The wake structure is analyzed in these various regimes, evidencing the existence of markedly different shedding modes according to the style of path. The variations of the drag force with the flow parameters is also examined, revealing that only one of the styles of path specific to very light spheres yields a non-standard drag behaviour, with drag coefficients significantly larger than those measured on a fixed sphere under equivalent conditions. The outcomes of this investigation are compared with available experimental and numerical results, evidencing points of consensus and disagreement.

Item Type:Article
Additional Information:Thanks to Cambridge University Press. The definitive version is available at : https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/path-oscillations-and-enhanced-drag-of-light-rising-spheres/77D39467B6AF521B681EF05B097B85F2
HAL Id:hal-01715490
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:22 Feb 2018 16:11

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