Structure factor of electrorheological fluids in compressive flow

This paper examines the chain structure factor evolution of electrorheological (ER) fluids in compressive flow. The yield strength of ER fluids was modeled based on a single pair electrostatic interaction between particles and the structure factor, which includes all the effects except the single pair electrostatic interaction between particles presented by the local electric field strength between particles. Both the mechanical and electrical properties of ER fluids in compressive flow have been experimentally determined. The nominal shear yield stress of the ER fluid in compressive flow was derived by assuming that it was a transformed shear flow of a Bingham fluid. The single pair particle interaction strength is related to the measured electric current, which reflects the local electric field strength between particles. The structure factor evolution in compressive flow was derived by comparing the nominal shear yield stress and the single pair particle interaction strength. As expected, the calculated structure factor increased significantly using this method, much higher than that described by the many-body effect and the difference of dipole-dipole interaction and multi-dipole interaction between particles. Direct mechanical contacts and frictional forces between particles are thought to contribute significantly to the high structure factor and nominal shear yield stress of the ER fluid in compressive flow. This behavior might be similar in magnetorheological (MR) fluids.