Electro-viscoelastic properties of dilute suspensions

Abstract

Suspensions of non-spherical particles can mimic viscoelastic behaviour when subjected to an electric field. When a steady shear is superimposed upon an oscillatory shear, different modes of viscoelastic behaviour are predicted depending on whether the applied electric field is subcritical or supercritical. For supercritical fields all particles oscillate about a steady-state orientation and the system exhibits time-independent linear viscoelasticity. For subcritical fields all particles execute complete rotations about their vorticity axis and, except for certain frequencies, the viscoelastic response is in general time-dependent. It is predicted that both the intrinsic dynamic viscosity and the dynamic rigidity can attain negative values, depending on particle shape and on the ratio of electric to hydrodynamic torques.