Journal
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
Volume 87, Issue -, Pages 16-34Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijmultiphaseflow.2016.08.005
Keywords
Non-spherical particles; Sedimentation; Particle pair interactions; Drafting-kissing-tumbling; Numerical modelling
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Funding
- European Research Council [ERC-2013-CoG-616186]
- COST Action MP1305: Flowing matter
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The gravity-driven motion of-rigid particles in a viscous fluid is relevant in many natural and industrial processes, yet this has mainly been investigated for spherical particles. We therefore consider the sedimentation of non-spherical (spheroidal) isolated and particle pairs in a viscous fluid via numerical simulations using the Immersed Boundary Method. The simulations performed here show that the critical Galileo number for the onset of secondary motions decreases as the spheroid aspect ratio departs from 1. Above this critical threshold, oblate particles perform a zigzagging motion whereas prolate particles rotate around, the vertical axis while having their broad side facing the falling direction. Instabilities of the vortices in the wake follow when farther increasing the Galileo number. We also study the drafting kissing-tumbling associated with the settling of particle pairs. We find that the interaction time increases significantly for non-spherical particles and, more interestingly, spheroidal particles are attracted from larger lateral displacements. This has important implications for the estimation of collision kernels and can result its increasing clustering in suspensions of sedimenting spheroids. (C) 2016 Elsevier Ltd. All rights reserved.
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