Viscous fingering on percolation clusters

The displacement of a high-viscosity fluid by a low-viscosity fluid leads to fractal viscous fingering in homogeneous porous media. A study of the viscous fingering at high and low displacement rates in percolating models that are inhomogeneous on all length scales makes it possible to construct different theoretical models for these two rates. Applying these two models to computer simulations on exactly the same geometry as in the experiments suggests that the underlying geometry determines the viscous fingering structure almost entirely.