The Real-Space Renormalization Group Applied to Diffusion in   Inhomogeneous Media
  The real-space renormalization group technique is introduced to evaluate the effective diffusion constant for diffusion in inhomogeneous media, which has been obtained by singular perturbation methods. Our method is formulated on a discretized real space and hence it can be easily combined with numerical studies for partial differential equations. 
Mitsuhiro Kawasaki