Multiparticle diffusive fractal aggregation

Kinetic fractal aggregation in a particle bath where a fraction f of the sites are initially occupied is studied with d=2 computer simulations. Independent particles diffusing to a fixed cluster produce an aggregate with fractal dimension D1.7 up to a correlation length (f). At larger lengths D2. (f) as f0. When the particles remain fixed but the cluster undergoes a rigid random walk, D appears constant at larger scales but varies with f. D1.95 at large f and D1.7 as f0. In both cases, the aggregate size N(t) grows with time t as t(f). © 1984 The American Physical Society.