Paper Number
SC21
Session
Suspensions and Colloids
Title
A thermodynamically consistent, microscopically-based model of aggregating particle suspension rheology
Presentation Date and Time
October 11, 2022 (Tuesday) 10:10
Track / Room
Track 1 / Sheraton 4
Authors
- Jariwala, Soham (University of Delaware, Chemical & Biomolecular Engineering)
- Wagner, Norman J. (University of Delaware, Chemical and Biomolecular Engineering)
- Beris, Antony N. (University of Delaware, Chemical & Biomolecular Engineering)
Author and Affiliation Lines
Soham Jariwala, Norman J. Wagner and Antony N. Beris
Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19711
Speaker / Presenter
Jariwala, Soham
Keywords
theoretical methods; colloids; suspensions
Text of Abstract
Aggregating colloidal suspensions can be encountered in a large number of materials; examples include food products, biological fluids, printer inks, paints, and slurries [1]. Modeling of these suspensions remains challenging as their rheology directly connects to the mesoscale structure and aggregation kinetics. Transient flows in such suspensions show complex dynamics due to yield stress, viscoelasticity, and flow history dependence, i.e., thixotropy.
In this work, we outline the development of a thermodynamically consistent, microscopically based, model for a suspension of aggregating particles under arbitrary inertia-less deformation. We show how the combination of a population balance-based description of the aggregating particle microstructure along with the use of the single generator bracket description of nonequilibrium thermodynamics [2] leads naturally to the formulation of the model equations. Notable elements of the model are: a lognormal distribution for the aggregate size population, a population balance-based model of the aggregation & breakup processes, and a conformation tensor-based viscoelastic description of the elastic network of the particle aggregates. The resulting model is evaluated against steady and transient shear rheology measurements of model thixotropic systems, such as fumed silica in paraffin oil and carbon black in mineral oil. Additionally, the thermodynamic consistency of this model is examined through entropy production. We also compare the entropy production between various dissipative phenomena involved in a typical flow process.
References - Mewis, J.; Wagner, N. J., Advances in Colloid and Interface Science 2009, 147-148, 214-227. DOI 10.1016/j.cis.2008.09.005.
- Beris, A. N.; Edwards, B. J., Thermodynamics of Flowing Systems: with internal Mircrostructure. Oxford University Press: 1994.