Brownian dynamics simulation of a dispersion composed of disk-like hematite particles regarding aggregation phenomena

Abstract

Abstract We have investigated aggregation phenomena in a suspension composed of disk-like hematite particles by means of Brownian dynamics simulations. The magnetic moment of the hematite particles lies normal to the particle axis direction, and therefore the present Brownian dynamics method takes into account the spin Brownian motion about the particle axis in addition to the ordinary translational and rotational Brownian motion. These particles are assumed to perform translational and rotational Brownian motion in a simple shear flow with addition of a uniform magnetic field applied in the direction normal to the shearing plane. The main results are summarized as follows. Significant column-like clusters are formed at a magnetic particle–particle interaction much larger than in the case of a magnetic spherical particle suspension. This is because the rotational Brownian motion has significant influence on the formation of clusters in a suspension composed of disk-like particles with large aspect ratio. An applied magnetic field is found to decrease the formation of column-like clusters. A shear flow is found not to have significant influence on the internal structures of clusters, but it does influence the cluster size distribution of the column-like clusters.