Dynamics of pore-scale protean droplets in porous media

We study a quasi-2D oil-in-water emulsion flowing through a microfluidic porous material, stabilized into droplets by a weak surfactant. The porous material creates droplet breakup against static obstacles, and the weak surfactant does not completely inhibit coalescence. Therefore, the droplets arrive at a steady-state size distribution, which is a function of the system geometry, flow speeds, and fluid properties. We show how parameters like capillary number, deformation, and collision symmetries, and relative positions of neighboring droplets relate to breakup and coalescence probabilities, and how the breakup and coalescence chances create our steady-state size distribution.