Effects of cluster trajectories on cluster-cluster aggregation: A comparison of linear and Brownian trajectories in two- and three-dimensional simulations

Recent computer simulation studies have shown that diffusion-limited particle-cluster aggregation leads to structures with a considerably smaller effective fractal dimensionality than particle-cluster aggregation via linear particle trajectories. Here it is shown that Brownian motion has a much smaller effect on the structure of aggregates formed as a result of cluster-cluster aggregation. In particle-cluster diffusion-limited aggregation, it is the particle trajectory which prevents the particles from penetrating and filling in the fractal cluster. In cluster-cluster aggregation, the clusters cannot penetrate each other by means of any trajectory so the particle trajectory is of much less importance.