The influence of particle size on diffusion-limited aggregation (DLA) has been investigated by computer simulations. For DLA clusters consisting of two kinds of particles with different sizes, when large particles are in the minority, the patterns of clusters appear asymmetrical and nonuniform, and their fractal dimensions $D_f$ increase compared with one-component DLA. With increasing size of large particles, $D_f$ increases. This increase can be attributed to two reasons: one is that large particles become new growth centers; the other is the big masses of large particles. As the concentration ratio $x_n$ of large particles increases, $D_f$ will reach a maximum value $D_{f_m}$ and then decrease. When $x_n$ exceeds a certain value, the morphology and $D_f$ of the two-component DLA clusters are similar to those of one-component DLA clusters.

• Received 2 March 1999

DOI:https://doi.org/10.1103/PhysRevE.60.6202