Tunable rheology of dense suspensions of conductive particles via an applied electric field

Electric-field-driven microhydrodynamics promises a novel approach to tune or control the suspension rheology of conductive particles. Upon the application of an electric field, these suspensions are known to undergo dipolophoresis (DIP), the combination of two nonlinear electrokinetic phenomena, namely induced-charge electrophoresis (ICEP) and dielectrophoresis (DEP). In this study, we perform large-scale numerical simulations of dense suspensions of ideally conductive particles undergoing DIP in the presence of shear flow using our Stokesian dynamics-based model. The control parameters are the magnitude, direction, and frequency of the electric field. When an electric field is applied along the shear-gradient direction, increasing the field magnitude results in a significant decrease in viscosity at low-frequency fields due to the dominant ICEP effect. Conversely, a high-frequency field leads to an increase in viscosity with the field magnitude due to the DEP dominance. It is also observed that changing the field direction leads to different rheological responses. We further analyze the effects of these control parameters on microstructure, normal stress differences, and suspension dynamics. Lastly, the transient behaviors resulting from sudden changes in the control parameters will be discussed.