MORPHOLOGY AND DYNAMICS OF INTERFACES IN RANDOM 2-DIMENSIONAL MEDIA

We study the morphology and dynamics of an interface driven through a disordered two-dimensional medium by an applied force. At large length scales the interface self-affine with roughness exponent alpha = 1/2. The structure at small scales may be self-similar or self-affine, dep ending on the degree of disorder. Simulations of wetting invasion prod uce self-affine interfaces with alpha = 0.8 and a power law distributi on of local interface velocities. Numerical results are in excellent a greement with experiment. A technique that distinguishes between true self-affine scaling and a crossover is presented, and applied to the i nvasion model and a model for magnetic domain growth.