Micro-capsules, which are fluid droplets enclosed in a thin elastic membrane, are current in nature (red blood cells, phospholipidic vesicles) and in various industrial applications (biotechnology, pharmacology, cosmetics, food industry). They are used to protect and transport active principles, by isolating them from the external suspending fluid. One application with high potential is the use of microcapsules for active substance targeting, but scientific challenges remain to be met, such as finding the optimal compromise between payload and membrane thickness, characterizing the membrane resistance and controlling the moment of rupture. Once injected in an external flow, the particles are indeed subjected to dynamical loading conditions, which result from the complex 3D capsule-flow interactions. One of the limitations of the numerical approaches currently used to predict the behavior of capsules subjected to an external flow comes from the fact that they do not consider capsule damage nor rupture.
The objective of the thesis project is to build a numerical model of the motion of a microcapsule suspended in flow and of its rupture. The microcapsule will be modeled as a liquid droplet enclosed in a thin membrane with hyperelastic properties. The challenges will be to account for the multiphysics phenomena governing the problem, which require solving for the inner and outer fluid flows, the deformation of the membrane, and crack initiation/propagation. It will allow to study the different phases of the capsule breakup (crack initiation, crack propagation, release of the inner content).