A study on the relation between flow characteristics and cluster formation of electrorheological fluid using visualization

Abstract

Electrorheological (ER) fluids show a rapid and reversible increase in viscosity when an electric field is applied. This is called the ER effect. The reason for the ER effect is the induction of an electric dipole in each particle, leading to the formation of clusters in the direction of the field, which resist fluid flow. Generally, the behavior of ER fluids has been modeled on those of Bingham plastics. However, there are some differences between Bingham plastics and ER fluids. The visualization of ER fluids is presented and ER effects of forming, growing, and breaking clusters are discussed. In the low-shear-rate area, the pressure drop is measured by two pressure sensors and the formation of ER particles is recorded with a video camera. The reason for the nonlinear behavior of ER fluids at low shear rate is explained through the results of the recording. As results, the behavior of ER fluids is nonlinear at low shear rate with an overshoot area because the strength of electric field causes clusters to form differently. The gap between electrodes becomes narrow because of the cluster layer occurrence near the electrodes under any conditions.