Structural Anisotropy of Aggregation Clusters

Abstract

The fractal description of the structure of aggregation clusters is incomplete, as it does not encompass the anisotropy of the clusters. Using simulated DLCA, RLCA and DLA clusters, we calculate a set of multipole expansion terms, to quantitatively evaluate the cluster anisotropy. Through examination of the scaling of these multipole terms, we show that the anisotropy of cluster-cluster aggregates is scale-invariant, while for DLA clusters of less that 10000 particles, the anisotropy decreases with increasing cluster size. We show that no new scaling exponents are required to determine the wavevector dependence of the multipole terms for cluster-cluster aggregates; only the fractal dimension is needed.