This talk briefly reviews the subject of fluid flow through disordered media. First, we use two-dimensional percolation networks as a simple model for porous media to investigate the dynamics of viscous penetration when the ratio between the viscosities of displaced and injected fluids is very large. The results indicate the possibility that viscous displacement through critical percolation networks constitutes a single universality class, independent of the viscosity ratio. We also focus on the sorts of considerations that may be necessary to move statistical physics from the description of idealized flows in the limit of zero Reynolds number to more realistic flows of real fluids moving at a nonzero velocity, when inertia effects may become relevant. We discuss several intriguing features, such as the surprisingly change in behavior from a "localized" to a "delocalized" flow structure (distribution of flow velocities) that seems to occur at a critical value of Re which is significantly smaller than the critical value of Re where turbulence sets in.
