Speaker
Antti Puisto
(Aalto University)
Description
In this presentation we will discuss the modeling of aggregation
and diffusion of particles under shear flow at continuum scale
using population balance based models. First, we will concentrate
on aggregation colloidal suspensions, specifically modeling the
state of fractally growing aggregates, and its implications to the
rheology of the fluid - for both orthokinetic and perikinetic
aggregation [1]. Furthermore, we will discuss the consequences
of such thixotropy caused by time-dependent aggregation to the
rheological characterization of the fluid. Then, we turn the
discussion to hard sphere suspensions. For these we have studied
shear induced migration of particles [2] in simple geometries,
and its influence on the experimentally measured flow curves.
With repulsive wall-particle interaction we observe the
appearance of shear rate dependent depletion layers near the
device walls [3]. For long time, in structured fluids this has been
modeled on sub-particle length scales, however, here we show
slip-layers of several tens of particle diameters, comparable to
experimental data observed, for instance, in stabilized emulsions
[4]. Furthermore, we will discuss the influence of this wall
depletion to the globally measured rheology.
[1] M. Mohtaschemi et al. Soft Matter 10, 2971 (2014).
[2] R. J. Phillips et al. Phys. Fluids A 4, 30 (1992).
[3] M. Korhonen et al. Under preparation (2014).
[4] S. Manneville et al. Eur. Phys. J. E 10, 209 (2003).
Primary author
Antti Puisto
(Aalto University)
