Paper Number
GG4
Session
Out of Equilibrium Systems: Gels and Glasses
Title
Frictional dynamics of sticky colloids
Presentation Date and Time
October 21, 2019 (Monday) 11:05
Track / Room
Track 7 / Room 306C
Authors
- Wang, Gerald J. (MIT, Chemical Engineering)
- Swan, James (MIT, Chemical Engineering)
Author and Affiliation Lines
Gerald J. Wang and James Swan
Chemical Engineering, MIT, Cambridge, MA 02139
Speaker / Presenter
Wang, Gerald J.
Text of Abstract
When two particles in a suspension approach contact, there is the possibility of a non-negligible (and perhaps even substantial) inter-particle frictional force. As a consequence, frictional forces can play a significant role in the structural and transport properties of systems that contain an appreciable number of particle-particle contacts, as is the case for suspensions at high particle volume fraction or with inter-particle attractions. Elucidating the relationship between microscopic frictional contact and macroscopic suspension properties is critical for understanding numerous rheological phenomena, most notably discontinuous shear thickening. Here, we present computational and theoretical modeling of frictional colloidal suspensions, in which friction is incorporated straightforwardly as a hydrodynamic resistance to sliding between nearly touching particles. Our simulations reveal that even a small amount of friction can dramatically decrease the diffusivity of both particles and particle clusters; more specifically, we observe a power-law scaling between the diffusivity suppression and the friction coefficient. This result is supported by a spectral model accounting for the effect of friction on the near-field components of the hydrodynamic resistance tensor. We also present evidence that friction gives rise to non-Gaussian particle displacement statistics, consistent with stick-slip dynamics. Moreover, we demonstrate that a combination of graph theory and classical rigidity theory can be applied to frictionally arrested particle clusters, in order to shed light on the conditions under which friction is especially important; in particular, we discuss the significance of system-spanning frictional clusters. We conclude by drawing comparisons between our work and experimental results from the literature, and by proposing fruitful avenues for joint computational-experimental work.