COMPUTER-SIMULATION OF STRUCTURES AND RHEOLOGICAL PROPERTIES OF ELECTRORHEOLOGICAL FLUIDS

The structural phase diagram of electrorheological (ER) fluids as a fu nction of dimensionless parameters lambda (the ratio of the dipolar fo rce to the Brownian force) and Pe (the ratio of the shear force to the Brownian force) is constructed. In the phase diagram, there exist thr ee single phases: a layerlike or chainlike crystalline phase (C), a sh ear-string phase (S), and a liquid phase (L). Between these single pha ses two phase coexistence zones of C+S and CS-L are located. The trans itions between the phases are driven by the competition between the di polar, shear, and Brownian forces. In the different phase zones,the vi scosity of the ER fluid has different dependencies on Pe and h. The ob served structures and corresponding rheological properties are discuss ed.