(322f) Dynamics of Suspensions of Elastic Capsules Flowing in Confined Geometries

Modeling the behavior of fluid-filled capsules (a simple representation of red blood cells and vesicles), is not only important to understand biological processes, such as blood flow in the microcirculation, but also to help design and improve microfluidic devices for characterizing such particles.

The present work describes simulations of large numbers of deformable capsules in Newtonian and viscoelastic fluids in confined geometries. Our algorithm incorporates a General-Geometry-Ewald-Like method (GGEM) for efficiently calculating hydrodynamic interactions (O(N)) in an immersed-boundary method. This allows for a detailed description of the particle interface combined with a large degree of freedom to model the complex geometry.

With our algorithm, we have addressed several issues. The ability to quickly simulate large number of particles enables examinations of not only the behavior of single particle, but also exploration of collision dynamics and concentration and confinement effects (capillary flows) on suspensions of such particles.

The effect of addition of long-chained polymer molecules in blood flow, known to affect hemodynamics, is also investigated. Preliminary results show that the effect of polymer is significant in single particle migration and pair collisions. Through our simulations we aim to gain a fundamental understanding of the viscoelastic effects on blood flow in the microcirculation.