Paper Number
PO26 

Session
Poster Session

Title
A multiscale model for the rheology of thixotropic suspensions

Presentation Date and Time
February 15, 2017 (Wednesday) 6:00

Track / Room
Poster Session / Foyer-Stairs/Windows

Authors (Click on name to view author profile)

1. Mwasame, Paul M. (University of Delaware, Department of Chemical and Biomolecular Engineering)
2. Wagner, Norman J. (University of Delaware, Chemical & Biomolecular Engineering)
3. Beris, Antony N. (University of Delaware, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Paul M. Mwasame, Norman J. Wagner, and Antony N. Beris
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716

Speaker / Presenter 
Mwasame, Paul M.

Text of Abstract
Complex fluids are increasingly common in many industrial processes and consumer products. Consequently, understanding the rheology of such systems is an important undertaking, and recently, there has been a renewed interest in modeling the rheology of thixotropic suspensions based on structure kinetic models [1,2,3]. Unfortunately, while some of these models have found utility in explaining experimental data, their predictions of large amplitude oscillatory shear (LAOS) and flow reversal do not accurately represent experimentally measured rheology [3]. Ultimately, these models fail to explicitly take into account the multiscale nature of the phenomena observed in thixotropic suspensions.

Accounting for the multiple length scale and associated dynamical responses at various experimental time scales requires the formulation of truly multiscale models. This contribution describes initial efforts on how a population balance model providing information on aggregation-breakage dynamics at the more microscopic level [4], a model for aggregate deformation and a consideration of the mesoscopic dynamics of colloidal aggregates can be systematically combined to model the macroscopic rheology of a thixotropic suspension. The additional information at the latter two levels is abstracted from a conformation tensor description, making the model potentially applicable to general flows. Comparison against experimental data including LAOS will also be discussed.

[1] Larson, R. G., Journal of Rheology 59.3 (2015): 595-611. [2] Wei, Y., M. J. Solomon, and R. G. Larson., Journal of Rheology 60.6 (2016): 1301-1315. [3] Armstrong, M. J., A. N. Beris, S. A. Rogers, and N. J. Wagner, Journal of Rheology 60.3 (2016): 433-450. [4] Mwasame, P. M., A. N. Beris, R. B. Diemer, and N. J. Wagner. "A constitutive equation for thixotropic suspensions with yield stress by coarse-graining a population balance model." Accepted AIChE Journal (2016).