Mercier, Matthieu and Wang, Shiyan and Péméja, Justin and Ern, Patricia
and Ardekani, Arezoo
Sedimentation of disks in a linearly stratified fluid.
(2020)
Journal of Fluid Mechanics, 885. 1-30. ISSN 0022-1120
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(Document in English)
PDF (Author's version) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader 4MB |
Official URL: https://doi.org/10.1017/jfm.2019.957
Abstract
We consider the unbounded settling dynamics of a circular disk of diameter d and finite thickness h evolving with a vertical speed U in a linearly stratified fluid of kinematic viscosity v and diffusivity k of the stratifying agent, at moderate Reynolds numbers (Re=Ud/v ). The influence of the disk geometry (diameter d and aspect ratio x = d/h ) and of the stratified environment (buoyancy frequency N, viscosity and diffusivity) are experimentally and numerically investigated. Three regimes for the settling dynamics have been identified for a disk reaching its gravitational equilibrium level. The disk first falls broadside-on, experiencing an enhanced drag force that can be linked to the stratification. A second regime corresponds to a change of stability for the disk orientation, from broadside-on to edgewise settling. This occurs when the non-dimensional velocity U/√vN becomes smaller than some threshold value. Uncertainties in identifying the threshold value is discussed in terms of disk quality. It differs from the same problem in a homogeneous fluid which is associated with a fixed orientation (at its initial value) in the Stokes regime and a broadside-on settling orientation at low, but finite Reynolds numbers. Finally, the third regime corresponds to the disk returning to its broadside orientation after stopping at its neutrally buoyant level.
Item Type: | Article |
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HAL Id: | hal-02524107 |
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 - Toulouse INP (FRANCE) Other partners > Purdue University (USA) Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE) |
Laboratory name: | |
Funders: | ANR project F-PISE (ANR-13-PDOC-023) - NSF CBET-16004423 and CBET-1705371 |
Statistics: | download |
Deposited On: | 30 Mar 2020 08:29 |
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