Critical role of flow-modified permittivity in electrorheology: model and computer simulation.

We propose a model that takes into account the effect of flow-modified permittivity (FMP) on electrorheology (ER). Our computer simulation shows that for Mason numbers less than 0.1, ER effects are mainly attributable to the deformation of chain structures, in agreement with earlier theoretical and simulation work. At larger Mason numbers, where chain structures have been destroyed by shear flows, we show that an FMP-induced misalignment between the particle dipole moments and the applied electric field plays a crucial role in producing ER effects. We also identify conditions under which negative ER effects are seen at large Mason numbers.