Self-expansion patterns of unconstrained assemblies of charged particulates are simulated by solution of their individual trajectories. The general behaviour of these systems is considered regarding their expansion shape and structure. As the particulates cannot be described, in general, in terms of massless charged entities, the complete equation of motion, inclusive of the inertial and other size effects, must be applied to each and every member of the assembly. It is shown that irrespective of the initial position of the particulates and the time dependent shape of the assembly, when expanding in free space or else the particulates are identical in size, shape and mass, they self-expand asymptotically into a circular or spherical shape with an inner structure that tends to uniformity. This behaviour persists irrespective of the size and charge level of the particulates, or whether they form a single or multiple separate groups in one, two and three dimensions. In this context, ionic gaseous assemblies that fit into the realm of continua, are included. Two- and three-dimensional examples of simulation outputs for different particulate assemblies, illustrate typical self-expansion patterns. Internal structures that evolve in two-dimensional self-expanding arrays are shown to be different compared to those obtained in three dimensions. These simulations show that models of particle capture by random self-expanding arrays of charged particulates, may lack physical grounds, as they contradict the asymptotic mode of uniform and ordered self-expansion that is expected from the array. (c) 2005 Elsevier Inc. All rights reserved.