Colloidal microdynamics: Pair-drag simulations of model-concentrated aggregated systems

Phys. Rev. E 56, 7067 – Published 1 December 1997
L. E. Silbert, J. R. Melrose, and R. C. Ball

Abstract

We report results of simulations of a model for concentrated aggregated colloidal dispersions under shear flows. In an effort to study trends in rheology for varying colloidal interactions, we study a reduced hydrodynamic, frame-invariant, pair-drag model in which a long-range, many-body mobility matrix is generated just from resistance pair-drag terms that include lubrication. The model also includes depletion interactions, repulsive surface forces, and Brownian forces. We consider the steady-state rheology of the model which we varied in volume fraction between 30% and 53%. We are able to fit our data to experimental results. The rheology of the model is that of a power-law shear-thinning fluid with relative viscosity scaling with shear rate as ηrγ̇-α and an exponent close to universal over a range of particle volume fractions 0.45–0.53. We also obtained a shear-thinning exponent that appears to be just weakly sensitive to the hydrodynamic model. The exponent α varies from 0.75±0.02 for weakly aggregating systems to 0.86±0.03 in the case of strong aggregating systems and the experimental data. As we lower the volume fraction we find a model-dependent transition to shear banding, where the rheology is effectively lost. We also find evidence of transitions between different shear-thinning regimes at the higher volume fractions when the particles are arranged in the familiar strings phases.

DOI: http://dx.doi.org/10.1103/PhysRevE.56.7067

  • Received 23 August 1996
  • Revised 2 September 1997
  • Published in the issue dated December 1997

© 1997 The American Physical Society

Authors & Affiliations

L. E. Silbert1, J. R. Melrose1, and R. C. Ball2

  • 1Polymers & Colloids Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
  • 2Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom

References (Subscription Required)

Authorization Required


×
×

Images

×

Log In

Cancel
×

Search


Article Lookup
Paste a citation or DOI

Enter a citation
×
  1. Enter a citation to look up or terms to search.

    Ex: "PRL 112 068103", "Phys. Rev. Lett. 112, 068103", "10.1103/PhysRevLett.112.068103"