ON ANOMALOUS DIFFUSION OF FRACTAL CLUSTERS UNDER CERTAIN REALISTIC PHYSICAL CONDITIONS

Diffusion of a fractal cluster of dimension dr in a three-dimensional space is investigated. The diffusion process is assumed to be modelled by a standard parabolic diffusion equation, although a more general c ase represented by the Fokker-Planck-Kolmogoroff equation is also intr oduced. The mean-square displacement of the cluster mass centre is ana lysed and its anomalous behaviour is presented and critically discusse d. The results obtained can be applied to describe some effects which may occur during the diffusion-limited cluster-cluster aggregation pro cess, especially when the viscosity of the solvent is changed in time and/or a directed transport of clusters is present in the system.