Buckling and its effect on the confined flow of a model capsule suspension

Spencer H. Bryngelson, Jonathan B. Freund

Research output: Contribution to journalArticlepeer-review


The rheology of confined flowing suspensions, such as blood, depends upon the dynamics of the components, which can be particularly rich when they are elastic capsules. Using boundary integral methods, we simulate a two-dimensional model channel through which flows a dense suspension of fluid-filled capsules. A parameter of principal interest is the equilibrium membrane perimeter, parameterized by ξo, which ranges from round capsules with ξo=1.0 to ξo=3.0 capsules with a dog-bone-like equilibrium shape. It is shown that the minimum effective viscosity occurs for ξo≈1.6, which forms a biconcave equilibrium shape, similar to a red blood cell. The rheological behavior changes significantly over this range; transitions are linked to specific changes in the capsule dynamics. Most noteworthy is an abrupt change in behavior for ξo≈2.0, which correlates with the onset of capsule buckling. The buckled capsules have a more varied orientation and make significant rotational (rotlet) contributions to the capsule–capsule interactions.

Original languageEnglish (US)
Pages (from-to)451-464
Number of pages14
JournalRheologica Acta
Issue number6
StatePublished - Jun 1 2016


  • Blood
  • Capsules
  • Numerical simulation
  • Suspensions

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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