Diffusion fronts and gradient percolation: A survey

Twenty years ago, Bernard Sapoval suggested that the solders obtained by inter-diffusion of two metals, could have a fractal structure. He, then, initiated simulation calculations based on a lattice gas model, describing the diffusion of non-interacting particles on a square lattice. These ideas are nowadays a mainstream field of research, developing in various domains including topics as different as fractal etching, imbibition experiments, fractal structures of polymer interfaces, image treatment, fracture surfaces, urban growth, predatory–prey interaction, etc.