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Fluid structure interaction of a microcapsule in flow
A capsule consists of an internal medium enclosed by a semi-permeable membrane that controls exchanges between the environment and the internal contents and has a protection role. Natural capsules are cells, bacteria or eggs. Artificial capsules are widely used in industry (pharmaceutical, cosmetic, food industry, etc) for the protection of active substances, aromas or flavours and the control of their release. They are also used in bioengineering applications, such as drug targeting and artificial organ fabrication.
In most situations, capsules are suspended into another liquid and are thus subjected to hydrodynamic forces when the suspension is flowing. The motion of the suspending and internal liquids creates viscous stresses on the membrane, which lead to its deformation and possible breakup. The three-dimensional fluid-structure interactions may be modelled coupling a boundary integral method (for the internal and external fluid motion) with a finite element method (for the membrane deformation), which we have shown to be a stable and accurate coupling strategy. We will concentrate on the case of ellipsoidal capsules and explore their motion and deformation when subjected to a simple shear flow.
When designing artificial capsules, it is also necessary to control and tune the capsule deformation, so that it has the desired behaviour. We will see how the mechanical properties of microcapsules can be obtained from a microfluidic experiment.