Abstract
Given the expanding applications of microfluidics in industrial and medical fields, studies that contribute to their understanding help with control and optimization of devices that rely on their principles. This thesis examines three problems relevant to particles interacting among themselves or with the microfluidic networks. The first chapter examines the role of particle deformability in clogging and failure of microfluidic devices with simple geometry. The coarse-grained deterministic model agrees with previous probability-based models and stochastic simulations. Depending on the flow conditions and feedback, deformable particles may have a different mean-time to clogging and the fraction of clogged channels at the time of failure may be different compared to rigid particles. The second chapter examines the role of applied pressure and shear stress threshold for erosion, a material-dependent property, in deposition of colloidal particles in packings of glass beads. The interplay between these two parameters may explain the two regimes observed in experiments, one with a uniform deposition of particles and one where the particles mostly deposit near the inlet. The last chapter investigates the role of particle size and G-actin diffusivity in collective behavior of actin-propelled beads. The model shows that larger particles may compete more for actin monomers which leads to increased interaction and flocking among them in close range.