Droplet Breakup and Coalescence Dynamics in a Porous Environment*

Emulsions are created by suspending small droplets in an immiscible bulk phase, where the droplets are often stabilized against breakup and coalescence by a surfactant. We study a water droplets-in-oil emulsion and its behaviors as we flow it through an obstacle matrix. This is done with a microfluidic system with quasi-2D drops, and obstacles that mimic porous rock and natural environments. We observe droplet coalescence and breakup, and study when this occurs while varying different droplet sizes and concentration, obstacle shapes, and pore sizes. We also characterize how these effects contribute to the bulk properties of the droplet flow.