Je. Martin et al., STRUCTURE AND DYNAMICS OF ELECTRORHEOLOGICAL FLUIDS, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 57(1), 1998, pp. 756-775
We have used two-dimensional light scattering to study the structure a
nd dynamics of a single-scattering electrorheological fluid in the qui
escent state and in steady and oscillatory shear. Studies of the quies
cent fluid show that particle columns grow in two stages; Particles fi
rst chain along the electric field, causing scattering lobes to appear
orthogonal to the field, and then aggregate into columns, causing the
scattering lobes to move to smaller angles. Column formation can be u
nderstood in terms of a thermal coarsening model we present, whereas t
he early-time scattering in the direction parallel to the field can be
compared to the theory of line liquids. In simple shear the scatterin
g lobes are inclined in the direction of fluid vorticity, in detailed
agreement with the independent droplet model of the shear thinning vis
cosity. In oscillatory shear the orientation of the scattering lobes v
aries nonsinusoidally. This nonlinear dynamics is described by a kinet
ic chain model, which provides a theory of the nonlinear shear rheolog
y in arbitrary shear flows.