Pore-Network Invasion: Capillary vs. Viscous Fingering

Push one fluid through the pore spaces of a rock or a packed bed, and its front does not stay flat unless conditions allow it to. This simulator models fluid displacement in porous media as an invasion process over a 3D lattice of pore sites: a non-wetting fluid injected from one face competes against a heterogeneous field of capillary entry thresholds and a viscous pressure gradient set by the capillary number and the viscosity ratio. Sweep the sliders to move between the three regimes of Lenormand's classic phase diagram — chaotic capillary fingering at low flow rates, runaway fractal viscous fingering when a thin fluid pushes a thick one fast, and broad, efficient stable displacement when a viscous invader is driven hard — while live readouts track invaded fraction, invasion steps and breakthrough at the outlet.