Computation of particle settling speed and orientation distribution in suspensions of prolate spheroids

E. Kuusela*, K. Höfler, S. Schwarzer

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

29 Citations (Scopus)

Abstract

A numerical technique for the dynamical simulation of three-dimensional rigid particles in a Newtonian fluid is presented. The key idea is to satisfy the no-slip boundary condition on the particle surface by a localized force-density distribution in an otherwise force-free suspending fluid. The technique is used to model the sedimentation of prolate spheroids of aspect ratio b/a = 5 at Reynolds number 0.3. For a periodic lattice of single spheroids, the ideas of Hasimoto are extended to obtain an estimete forthe finite-size correction to the sedimentation velocity. For a system of several spheroids in periodic arrangement, a maximum of the settling speed is found at the effective volume fraction Φ(b/a)2 ≈ 0.4, where Φ is the solid-volume fraction. The occurence of a maximum of the settling speed is partially explained by the competition of two effects: (i) A change in the orientation distribution of the prolate spheroids whose major axes shift from a mostly horizontal orientation (corresponding to small sedimentation speeds) at small Φ to a more uniform orientation at larger Φ, and (ii) a monotonic decrease of the settling speed with increasing solid-volume fraction similar to that predicted by the Richardson-Zaki law α (1 - Φ)5.5 for suspensions of spheres.

Original languageEnglish
Pages (from-to)221-235
Number of pages15
JournalJOURNAL OF ENGINEERING MATHEMATICS
Volume41
Issue number2-3
DOIs
Publication statusPublished - 1 Nov 2001
MoE publication typeA1 Journal article-refereed

Keywords

  • Ellipsoids
  • Fibers
  • Finite differences
  • Particle scale simulation
  • Sedimentation
  • Spheroids
  • Suspensions

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