3D modeling of droplet flow in confined geometry

An improved understanding of the behavior of capillary droplets in microfluidic devices will enable advances in cell sorting, disease diagnostics, and nanoparticle synthesis. In this work, we develop a deformable particle model to simulate surface tension-driven shape changes and break-up in three dimensional (3D) oil droplets in water flowing through narrow constrictions and obstacle arrays. We first show that the shapes and speeds of the centers of mass of the droplets in the simulations match those of the experimental droplets flowing through narrow constrictions to less than 5% error. For the droplet simulations, we implement surface triangle-boundary interactions to prevent large overlaps between the droplet and boundary and include droplet breakup due to large droplet deformations using an energy-based break-up criterion. We will use the experimentally-validated simulations of a single droplet flowing through a narrow constriction and flowing past a single obstacle to study clogging and breakup as multiple droplets flow through obstacle arrays. Preliminary computational studies in 2D in the absence of droplet breakup suggest that the permeability of the obstacle array to droplet flow scales with the porosity of the array. We expand these studies to 3D with droplet break-up to determine how dimensionality and break-up impact the relationship between permeability and porosity.