Diffusion-limited aggregation with surface tension

Computer simulations of diffusion-limited aggregation (DLA) show that surface tension, as a short-range interaction, does not change the fractal structure for large aggregates. Clusters grown with surface tension develop three regions. (1) At the center, the cluster is compact and regular; the effective fractal dimension $D_f^{\mathrm{eff}}$ is close to 2. (2) Next to the center is a transition region where $D_f^{\mathrm{eff}}$ decreases quickly from 2 to about 1.70±0.05. (3) Past the transition region, the cluster grows as a DLA fractal and $D_f^{\mathrm{eff}}$ extrapolates to 1.70±0.05. An increased surface tension is found to produce clusters with rounder shapes, thicker fingers, and larger compact centers. The thickness of the fingers and the size of the compact center are determined theoretically, and these estimations compare well with results obtained from the numerical simulations.