Paper Number
SC16 

Session
Suspensions and Colloids

Title
Rheology of non-Brownian particles suspended in a colloidal shear thickening fluid

Presentation Date and Time
October 7, 2014 (Tuesday) 10:00

Track / Room
Track 1 / Commonwealth A

Authors (Click on name to view author profile)

1. Cwalina, Colin D. (University of Delaware, Department of Chemical and Biomolecular Engineering)
2. Wagner, Norman J. (University of Delaware, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Colin D. Cwalina and Norman J. Wagner
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Speaker / Presenter 
Cwalina, Colin D.

Text of Abstract
Suspensions of non-Brownian particles in non-Newtonian fluids show a varied and rich flow behavior that often reflects the rheological properties of the suspending fluid. To date, such investigations have largely focused on matrices consisting of shear thinning and Boger fluids. Of significant interest is the link between the rheological properties of the suspension and non-trivial microstructures that develop as a consequence of hydrodynamic interactions between particles in the non-Newtonian suspending fluid [Van Loon et al. (2013)]. In the current work, we investigate the rheological consequences of adding non-Brownian spheres to moderately concentrated colloidal dispersions under shear flow. This particular choice of suspending fluid is novel in that it exhibits both shear thinning and shear thickening. In the range of non-Brownian particle volume fractions investigated, we find that the critical stress for the onset of shear thickening in these suspensions is identical to that of the pure colloidal dispersion, while the critical shear rate is a decreasing function of the volume fraction. These findings are of practical significance as many industrial processes and materials (e.g. cement) consist of suspensions of mixtures of colloidal and non-Brownian particles.