Paper Number
SC23 

Session
Suspensions, Colloids, and Granular Materials

Title
Modeling the flow of aggregating suspensions using a multiscale tensor approach

Presentation Date and Time
October 12, 2021 (Tuesday) 2:45

Track / Room
Track 5 / Ballroom 6

Authors (Click on name to view author profile)

1. Jariwala, Soham (University of Delaware, Chemical & Biomolecular Engineering)
2. Armstrong, Matthew J. (United States Military Academy, Department of Chemistry and Life Science)
3. Wagner, Norman J. (University of Delaware, Chemical & Biomolecular Engineering)
4. Beris, Antony N. (University of Delaware, Chemical & Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Soham Jariwala¹, Matthew J. Armstrong², Norman J. Wagner¹ and Antony N. Beris^1
1Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716; ²Department of Chemistry and Life Science, United States Military Academy, West Point, NY 10996

Speaker / Presenter 
Beris, Antony N.

Keywords
theoretical methods; colloids; non-Newtonian fluids; suspensions

Text of Abstract
Thixotropy, viscoelasticity, and yield stress result in complex fluid flow behavior in aggregating suspensions. Numerous phenomenological models accurately describe aggregating suspension rheology by employing scalar structure parameters; however, a general model that incorporates the physics of aggregation and breakage remains to be explored. Previous work by Mwasame et al. [1] that uses a model based on population balances that shows good agreement with the shear rheometry experiments. This approach also replaces some empiricism in the structure kinetics approach with a more physically informed modeling. A full tensor description would allow one to go beyond rheometric flows and model fluid flows in arbitrary geometries. A promising framework has been proposed by Stephanou and Georgiou [2], where the authors have derived a non-equilibrium thermodynamics (NET) based constitutive model that uses a conformation tensor to describe the mesoscale structure and thixotropy in thermodynamically consistent fashion.

In this work, we show that a population balance based rheological model can be recast such that the aggregation and breakage kernels are consistent with NET [3] framework. Specifically, we address the breakage kernel, which has been shown to scale as a function of stress for both shear and extensional flows [4]. The resulting tensorial model can potentially describe macroscopic flows in arbitrary three-dimensional geometries. The model predictions for both simple shear and uniaxial extensional flow are compared against the existing models. As non-equilibrium thermodynamics offers a more consistent tensor description, we also explore how the model can capture flow inhomogeneities and effects such as stress-induced migration.

References:
1. Mwasame, Beris, Diemer and Wagner, AIChE J., 2017, 63, 517-531
2. Stephanou and Georgiou, J. Chem. Phys., 2018, 11
3. Beris and Edwards, Thermodynamics of flowing systems, Oxford University Press, 1994
4. Harshe and Lattuada, Langmuir, 2012, 28,283-292