Flocculation and Gelation in Cluster Aggregation

Abstract

Clustering of clusters is introduced as a model to describe irreversible diffusion-limited aggregation of clusters. The scaling properties are determined using numerical simulations and mean field arguments. The results are compared with the Smoluchowski equation approach. The scaling behavior is different for low cluster concentration (flocculation) and for high cluster concentration ('gelation'). Reversible cluster aggregation can be modelled by randomly breaking bonds. This leads to a different cluster structure, with scaling behavior like lattice animals. The clusters of irreversible cluster and particle (DLA) aggregation are investigated for their internal anisotropy: particle aggregates appear to scale differently parallel and perpendicular to the direction of growth