Steady-state, simultaneous two-phase flow in porous media: experiment and simulation

We report on experimental and numerical studies of steady-state two-phase flow in a quasi twodimensional porous medium. Experimentally, the wetting and the non-wetting phase are injected simultaneously from alternating inlet points into a Hele-Shaw cell containing one layer of randomly distributed glass beads, initially saturated with wetting fluid. Transient behavior is observed in time and space, such that at a certain distance behind the front, fully developed fragmented steady-state flow develops. Numerical studies confirm this transition and support the conclusion that the steadystate phase is fragmented and dominated by bubble dynamics, allowing for a statistical description on the meso-scopic scale in terms of effective behavior and on the micro-scale in terms of cluster-size distributions. The latter is shown to obey a scaling-law with the Darcy velocity.