Electrostatic particle-particle interactions in electrorheological fluids

Abstract

A model for the particle‐particle interaction in a chain of spherical particles in an electrorheological (ER) fluid is developed based on an expansion of the potential which satisfies the Laplace equation. The electric‐field distribution and force‐distance relationship between particles are calculated as a function of K_p/K_f (the dielectric constant of the sphere relative to that of the medium) and particle‐particle spacing using this model. The calculations predict electric‐field concentrations of about an order of magnitude near particle contacts. This gives a force between particles that is approximately an order of magnitude higher than predicted by the classical point‐dipole approximation, and is in reasonable agreement with that measured experimentally. Subtle effects of the carrier fluid on the interaction force and an explanation for the non‐Ohmic behavior of ER fluids are deduced in terms of its dielectric constant and dielectric strength.