Paper Number
PO61
Session
Poster Session
Title
A microstructural analysis of shear thickening
Presentation Date and Time
October 12, 2022 (Wednesday) 6:30
Track / Room
Poster Session / Riverwalk A
Authors
- Buchholtz, William (Georgetown University, Institute for Soft Matter Synthesis and Metrology)
- Vinutha, H A (Georgetown University, Institute for Soft Matter Synthesis and Metrology)
- Urbach, Jeffrey (Georgetown University, Institute for Soft Matter Synthesis and Metrology)
- Blair, Daniel (Georgetown University, Institute for Soft Matter Synthesis and Metrology)
- Del Gado, Emanuela (Georgetown University, Department of Physics)
Author and Affiliation Lines
William Buchholtz, H A Vinutha, Jeffrey Urbach, Daniel Blair and Emanuela Del Gado
Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC
Speaker / Presenter
Buchholtz, William
Keywords
computational methods; jammed systems; suspensions
Text of Abstract
Considerable research has been done to understand and predict shear thickening in particle suspensions. Despite this, a complete understanding of the microstructural underpinnings of thickening is lacking. To investigate how the macroscopic flow of a suspension arises from its microstructure (particularly the geometry of the particle positions and contacts) we identify and simulate a simple system where shear thickening is observed to occur: frictional disks emerged in a solvent (modeled only through its overall viscosity) at densities near but below jamming. At these densities a thickening to thinning transition is observed as the shear rate is increased allowing us to compare the structure of the materials in different flow regimes but at the same density. In the thickening regime the pair correlation function g(r) develops sharp peaks at distances corresponding to particle chains while in the thinning regime these peaks broaden and resemble the g(r) of an un-sheared suspension. In addition, several other quantities are compared across the regimes such as the local average contact number “q”, the distribution of disk loops, disk rotations, and non-affine velocities. Collectively these metrics suggest that there are microstructure differences between suspensions that thicken and those that thin. Therefore, our current work seeks to analyze how the structures characteristic of thickening result in stress build-up. Particular interest is also given to the remarkable flow at intermediate shear rates where the suspensions intermittently switch between high stress and low stress states.