Simulation of the athermal coarsening of composites structured by a uniaxial field

We report the results of a computer simulation of the evolution of structure in a two component fluid consisting of a liquid phase and a dispersed colloidal phase subjected to a uniaxial field. Our primary objective is to understand the mechanism and kinetics of coarsening and the emergence of crystallinity, Using an efficient, linear-N simulation method we report studies of systems of N = 10 000 particles over the concentration range of 10-50 vol %. We present a variety of methods. of characterizing the structures that emerge, including the anisotropy of the conductivity, capacitance and dipolar interaction energy, the two-dimensional pair correlation function, principal moments of the gyration tensor, velocity correlation functions, microcrystallinity and coordination number, and the optical attenuation length. We conclude that athermal coarsening is effectively driven by the presence of defect structures and that as the concentration increases, the structures progressively lose the well-known "chain" anisotropy evinced at low concentration. (C) 1998 American Institute of Physics.