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A cloud of rigid fibres sedimenting in a viscous fluid

Published online by Cambridge University Press:  07 April 2010

JOONTAEK PARK ,
BLOEN METZGER ,
ÉLISABETH GUAZZELLI  and
JASON E. BUTLER
JOONTAEK PARK
Affiliation:
Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA
BLOEN METZGER*
Affiliation:
IUSTI-CNRS UMR 6596, Polytech-Marseille, Aix-Marseille Université (U1), Technopôle de Château-Gombert, 13453 Marseille cedex 13, France
ÉLISABETH GUAZZELLI
Affiliation:
IUSTI-CNRS UMR 6596, Polytech-Marseille, Aix-Marseille Université (U1), Technopôle de Château-Gombert, 13453 Marseille cedex 13, France
JASON E. BUTLER
Affiliation:
Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA
*
†Email address for correspondence: [email protected]
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Abstract

Experiments and numerical simulations have been performed to investigate the deformation and break-up of a cloud of rigid fibres falling under gravity through a viscous fluid in the absence of inertia and interfacial tension. The cloud of fibres is observed to evolve into a torus that subsequently becomes unstable and breaks up into secondary droplets which themselves deform into tori in a repeating cascade. This behaviour is similar to that of clouds of spherical particles, though the evolution of the cloud of fibres occurs more rapidly. The simulations, which use two different levels of approximation of the far-field hydrodynamic interactions, capture the evolution of the cloud and demonstrate that the coupling between the self-motion and hydrodynamically induced fluctuations are responsible for the faster break-up time of the cloud. The dynamics of the cloud are controlled by a single parameter which is related to the self-motion of the anisotropic particles. The experiments confirm these findings.

JFM classification

Instability: Instability
Type
Papers
Information
Journal of Fluid Mechanics , Volume 648 , 10 April 2010 , pp. 351 - 362
Copyright
Copyright © Cambridge University Press 2010

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References

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Park et al. supplementary movie

Movie 1. Fiblet simulation of the sedimentation of a cloud of fibres for c=40 and N_0=1000. (left) side view, (right) bottom view.

Download Park et al. supplementary movie(Video)
Video 289.2 KB

Park et al. supplementary movie

Movie 1. Fiblet simulation of the sedimentation of a cloud of fibres for c=40 and N_0=1000. (left) side view, (right) bottom view.

Download Park et al. supplementary movie(Video)
Video 23.4 MB

Park et al. supplementary movie

Movie 2. Sedimentation of a cloud of copper fibres in a viscous fluid. The movie starts just prior the break-up. The fibre length is typically 1.3 mm.

Download Park et al. supplementary movie(Video)
Video 4.4 MB

Park et al. supplementary movie

Movie 2. Sedimentation of a cloud of copper fibres in a viscous fluid. The movie starts just prior the break-up. The fibre length is typically 1.3 mm.

Download Park et al. supplementary movie(Video)
Video 45.6 MB