Deformation of a capsule in simple shear flow : Effect of membrane prestress

E. Lac (1) , D. Barthès-Biesel (1)

1 BIM - Biomécanique et génie biomédical

We investigate the effect of an initial isotropic prestress on the mechanics of a spherical capsule freely suspended in a simple shear flow. The capsule consists of a drop of liquid enclosed by a very thin hyperelastic membrane. A sufficient prestress may prevent the buckling instability that arises at low shear rates when the membrane bending resistance is neglected. A small perturbation analysis of the capsule deformation is first obtained for small prestress and weak viscous stresses. When the viscous shear stress and the preinflation are large, a numerical model of the capsule deformation shows how prestress decreases the capsule deformation for a given shear rate and how it significantly increases the elastic tension in the membrane at a given deformation level. These results may help the experimentalists to detect the presence of an osmotic pressure difference in a semipermeable capsule.

Mots clés: Deformation; Shear modulus; Numerical methods; Perturbation analysis; Osmosis; Polymers; Interfacial tension; Fluid flows; Viscosity

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

E. Lac, D. Barthès-Biesel. Deformation of a capsule in simple shear flow : Effect of membrane prestress. Physics of Fluids, 2005, 17, pp.1-8. ⟨10.1063/1.1955127⟩. ⟨hal-00014803⟩