Hydrodynamic interactions and membrane damage for a pair of microcapsules in shear flow: Effect of membrane mechanical properties

We model the hydrodynamic interaction of two equal size capsules in simple shear flow. The capsules may have different mechanical membrane properties. The results are analyzed in terms of a macro scale model of capsule membrane damage. We show how the interaction between two capsules with a membrane rigidity mismatch may lead to damage of the more deformable capsule even when the base flow strength is below the damage threshold of both capsules. We provide charts of the peak deformation energy density in the two membranes as a function of the flow strength and the ratio of the elastic rigidity of the two capsules. Given a damage criterion, those charts can be used to determine when flow-induced damage will occur in a suspension of capsules with a distribution of mechanical properties.