Brownian Dynamics Simulations of Ferromagnetic Colloidal Dispersions in a Simple Shear Flow.

We have carried out Brownian dynamics simulations to investigate the behavior of clusters of ferromagnetic particles in a colloidal dispersion subjected to a simple shear flow. The results have been compared with those of Stokesian dynamics and Monte Carlo simulations. The main results obtained here are summarized as follows. The Brownian dynamics method can capture thick chain-like clusters formed along a magnetic field, in agreement with the Stokesian dynamics and Monte Carlo methods. However, Brownian motions of the particles give a subtle influence on the internal structure of thick chain-like clusters even in the case in which the magnetostatic interactions dominate the particle Brownian motions. The Stokesian dynamics method leads to a physically unreasonable cluster formation in the case in which the particle Brownian motions play an important role compared with that of the magnetic particle-particle interactions. We conclude that the Brownian dynamics method gives rise to physically realistic cluster formations in simulation of colloidal dispersions and therefore the method is to be preferred to the Stokesian dynamics method. Copyright 1999 Academic Press.