Numerical study on microstructures and their rheological properties in electrorheological fluids

Abstract

We study the relation between microstructures of electrorheological (ER) fluids and their viscosity change by performing Brownian dynamics simulations of a model ER system both in a static state and in a simple steady shear. From large-scale three-dimensional simulations, it is found that (1) under no shear flow there are two principal phases in microstructural changes: first aggregation of particles into chains oriented along the field direction, and the subsequent slow coalescence of chains into columns, and (2) under a simple steady shear there are three stages in viscosity changes with increasing the field: Newtonian at a weak field, non-Newtonian at a moderate field, and Bingham plastic with yield stress at a high field.