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Large deformations and burst of a capsule freely suspended in an elongational flow

Published online by Cambridge University Press:  21 April 2006

X. Z. Li
Affiliation:
Division de Biomécanique (U.A. CNRS 858), Université de Technologie de Compiègne, BP 649 60206 Compiègne, France
D. Barthes-Biesel
Affiliation:
Division de Biomécanique (U.A. CNRS 858), Université de Technologie de Compiègne, BP 649 60206 Compiègne, France
A. Helmy
Affiliation:
Division de Biomécanique (U.A. CNRS 858), Université de Technologie de Compiègne, BP 649 60206 Compiègne, France

Abstract

An axisymmetric capsule, consisting of an incompressible liquid droplet, surrounded by an infinitely thin elastic membrane having a Mooney constitutive behaviour, is suspended into another incompressible Newtonian liquid subjected to an elongational shear flow. The motion and the deformation of the capsule are determined numerically by means of a boundary-integral technique. It is thus possible to reach large deformations, and to study the influence of the initial geometry of the particle, as well as that of the constitutive behaviour of the membrane. In all cases considered here, it appears that there exists a critical value of the non-dimensional shear rate (the capillary number) above which no steady solution can be obtained, and where the capsule continuously deforms. This phenomenon is interpreted as the outset of burst. The model shows also the importance of the sphericity index for the determination of the overall capsule deformability.

Type
Research Article
Copyright
© 1988 Cambridge University Press

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