Flexible particles (FP) including capsules, vesicles and cells are small droplets enclosed by thin membranes. They are widely found in nature and have numerous applications in food, cosmetic, textile, biomedical and pharmaceutical industries (e.g. drug delivery and release). In many applications FPs are subjected to external flows wherein quantities such as the local membrane stress and the internal and surrounding flow fields are very difficult to measure experimentally. However, these are critical parameters in many fields, for instance in the rupture control of capsules in flow (e.g., capsule breakup for drug release, damage of artificial red blood cells during circulation). Accurate mechanical modelling can provide reliable and detailed information on capsule motion, membrane stress and flow field, thereby serving as an essential component for the design, optimization and fabrication of FPs. However, this is very challenging since it involves strong interaction between the viscous fluids and an FP membrane, which is a thin solid shell and usually undergoes large deformation.

The aims of present research mainly include:

1. To develop accurate mechanical modelling and a software tool for the simulation of the dynamics of FPs in flow;
2. To study the motion of FPs with different mechanical properties under various flow conditions and geometries, which will help to improve the understanding of FP dynamics and thus facilitate the design and optimization of FPs in various industrial sectors;
3. To study the rheology of FPs suspensions from direct numerical simulation, benchmark existing asymptotic theories and propose new reduced constitutive models;
4. To develop microfluidic devices for fabricating micro FPs with tailor-made mechanical properties, and for trapping or separating of cells;
5. To investigate the complex mechanism of cell-cell, cell-wall interactions.