STRUCTURE FORMATION IN ELECTRORHEOLOGICAL FLUIDS

Electrorheological fluids are colloidal suspensions of polarizable particles in a viscous, nonconductive solvent. When an electric field is applied to a fluid, dielectric columns form, oriented parallel to the field. One can calculate the size of the columns formed in two dimensions using a simple model. I also discuss possible mechanisms for the long-term relaxation of the fluid toward a phase separated state. This paper then compares these predictions with the results of a molecular dynamics simulation of the aggregation process. The simulation differs from most others performed previously in that it examines structure formation near equilibrium. The simulation provides confirmation of the predicted column sizes in the dilute, near-equilibrium limit and provides a measure of the time scale for phase separation. The observed time scale is independent of field strength, supporting an interpretation that phase separation is driven by an interaction between the thermal fluctuations of the shape of separated columns. © 1993 Academic Press. All rights reserved.