CONVEX TO CONCAVE TRANSITION AND INVARIANT DISTRIBUTION OF SEGMENT LENGTHS IN MANY-WALKER ANISOTROPIC DIFFUSION-LIMITED AGGREGATION

We present numerical studies of an on-lattice many-walker diffusion-li mited aggregation model. For asymptotic late stage growth, the ensembl e averaged envelope exhibits a convex to concave transition. This tran sition resembles morphology transitions in other diffusion-limited sys tems but we do not detect a change in the functional form of the growt h velocity. We also find that the distribution of the segment lengths is invariant under changes of the supersaturation.