Interface Shapes in Microfluidic Porous Media: Conditions Allowing Steady, Simultaneous Two-Phase Flow

Abstract Microfluidic devices offer unique opportunities to directly observe multiphase flow in porous media. However, as a representation of geological pore networks, conventional microfluidics face several challenges. One is whether steady simultaneous two-phase through two-dimensional network possible without fluctuating occupancy the constrictions. Flow fluctuations can occur only if paths two phases cross on 2D network; this requires that wetting phase form bridge across gap between grains at constriction while non-wetting flows constriction. We consider conditions under which function local capillary pressure and geometry Using Surface Evolver software, we determine for stable interfaces constricted geometries, range pressures bridging occur, those where would re-invade block (“snap-off”). If long either straight or uniformly curved, snap-off occurs same bridging. For constrictions concave shape, represent cylindrical grains, however, find stable; greater narrower diameter cylinders (i.e. more strongly throat) relative width smaller-diameter pillars, phenomenon “Roof” invades downstream body, predicted not occur.