Dynamics of a non-spherical microcapsule with incompressible interface in shear flow

P. M. Vlahovska*, Y. N. Young, G. Danker, C. Misbah

*Corresponding author for this work

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

We study the motion and deformation of a liquid capsule enclosed by a surface-incompressible membrane as a model of red blood cell dynamics in shear flow. Considering a slightly ellipsoidal initial shape, an analytical solution to the creeping-flow equations is obtained as a regular perturbation expansion in the excess area. The analysis takes into account the membrane fluidity, area-incompressibility and resistance to bending. The theory captures the observed transition from tumbling to swinging as the shear rate increases and clarifies the effect of capsule deformability. Near the transition, intermittent behaviour (swinging periodically interrupted by a tumble) is found only if the capsule deforms in the shear plane and does not undergo stretching or compression along the vorticity direction; the intermittency disappears if deformation along the vorticity direction occurs, i.e. if the capsule 'breathes'. We report the phase diagram of capsule motions as a function of viscosity ratio, non-sphericity and dimensionless shear rate.

Original languageEnglish (US)
Pages (from-to)221-247
Number of pages27
JournalJournal of fluid Mechanics
Volume678
DOIs
StatePublished - Jul 10 2011

Keywords

  • Capsule/cell dynamics

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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