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Inertial torques and a symmetry breaking orientational transition in the sedimentation of slender fibresPublished in Cambridge University Press

2019

DOI: 10.1017/jfm.2019.492

Volume: 875

Pages: 576 - 596

Experimental measurements of the force and torque on freely settling fibres are compared with predictions of the slender-body theory of Khayat & Cox (J. Fluid Mech., vol. 209, 1989, pp. 435-462). Although the flow is viscous dominated at the scale of the fibre diameter, fluid inertia is important on the scale of the fibre length, leading to inertial torques which tend to rotate symmetric fibres toward horizontal orientations. Experimentally, the torque on symmetric fibres is inferred from the measured rate of rotation of the fibres using a quasi-steady torque balance. It is shown theoretically that fibres with an asymmetric radius or mass density distribution undergo a supercritical pitch-fork bifurcation from vertical to oblique settling with increasing Archimedes number, increasing Reynolds number or decreasing asymmetry. This transition is observed in experiments with asymmetric mass density and we find good agreement with the predicted symmetry breaking transition. In these experiments, the steady orientation of the oblique settling fibres provides a means to measure the inertial torque in the absence of transient effects since it is balanced by the known gravitational torque. © 2019 Cambridge University Press.

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About the journal

Journal | Data powered by TypesetJournal of Fluid Mechanics |
---|---|

Publisher | Data powered by TypesetCambridge University Press |

ISSN | 00221120 |

Open Access | No |

Concepts (20)

- Bifurcation (mathematics)
- Bodies of revolution
- Capillary flow
- Reynolds number
- Torque
- FORCE AND TORQUES
- GRAVITATIONAL TORQUE
- ORIENTATIONAL TRANSITIONS
- PARTICLE/FLUID FLOWS
- PITCH-FORK BIFURCATIONS
- SLENDER-BODY THEORY
- SYMMETRY BREAKING TRANSITION
- Symmetry-breaking
- Fibers
- Bifurcation
- Experimental study
- Flow modeling
- Fluid flow
- Numerical model
- Sedimentation