Simulations of electrorheological and particle mixture suspensions: Agglomerate and layer structures

Brownian dynamics (BD) simulations have been carried out of the rheology of two model weakly aggregated suspensions—model electrorheological (ER) fluids with anisotropic dipole interactions and depletion flocculated (DF) systems with isotropic well potential interactions. At rest, both systems form an infinite gel‐like aggregate network. Under shear, they shear thin and undergo shear‐induced agglomeration to structures more compact than the gels at rest. The present work reports simulations of much larger model systems (N=500) than considered previously and makes a comparison between the two systems under shear. We investigate a range of volume fractions in the ER case and elucidate further the microscopic mechanisms of flow in the ER and DF cases. In the case of ER fluids at 10% and 30% volume fraction, layer structures form normal to the vorticity axis at low shear. These are not found at 50% volume fraction. The layer transition is associated with some hysteresis in the Stokesian (large particle/high s...

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