Two‐phase flow in porous media

Two‐phase flow in porous media depends on many factors, such as displacement vs steady two‐phase flow, saturation, wettability conditions, wetting fluid vs non‐wetting fluid is displacing, the capillary number, interfacial tension, viscosity ratio, pressure gradient, uniformly wetted vs mixed‐wet pore surface, uniform vs distributed pore throats, small vs large pores, well‐connected pores vs pores connected by small throats, etc. These parameters determine how the two fluids are distributed in the pores, e.g. whether they flow in seperate channels or side‐by‐side in the same channels, either with both fluids being continous or only one fluid being continous and the other discontinuous. In displacement, the capillary number and the viscosity ratio determine whether the displacement front is sharp, or if there is either capillary or viscous fingering.