Abstract
Analytical results for the apparent slip between two spheres in a simple biviscous model of a shear-thinning fluid are presented. Velocity profiles and apparent slip lengths along the surfaces are analyzed in order to characterize the physical mechanism. It is shown that in this non-Newtonian model, the effect of shear thinning limited to high-shear rates in the interstitial regions between close spheres can be alternatively interpreted as the onset of an apparent shear-rate-dependent slippage effect. The results of the theory compare well with experiments from the literature showing the presence of surface slip on a particle approaching a planar wall. In terms of implications for suspensions rheology, the present results bridge the “hidden” solvent shear-thinning theory [Vázquez-Quesada et al., Phys. Rev. Lett. 117, 108001 (2016)] with slip-based models presented recently [Kroupa et al., Phys. Chem. Chem. Phys. 19, 5979 (2017)] as a possible explanation for the mechanism behind the shear thinning in hard-sphere non-Brownian suspensions.
- Received 21 March 2018
DOI:https://doi.org/10.1103/PhysRevFluids.3.123302
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