Colloidal microdynamics : pair-drag simulations of model-concentrated aggregated systems
Silbert, L. E., Melrose, John R. and Ball, Robin. (1997) Colloidal microdynamics : pair-drag simulations of model-concentrated aggregated systems. Physical Review E, Vol.56 (No.6). pp. 7067-7077. ISSN 1063-651XFull text not available from this repository.
Official URL: http://dx.doi.org/10.1103/PhysRevE.56.7067
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 ηr∼γ̇-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.
|Item Type:||Journal Article|
|Subjects:||Q Science > QC Physics|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Colloids, Shear flow, Rheology, Simulation methods|
|Journal or Publication Title:||Physical Review E|
|Publisher:||American Physical Society|
|Page Range:||pp. 7067-7077|
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