Paper Number
DP17                         My Program 

Session
Dense Particulate Systems

Title
Investigating the microstructure of attractive and frictional dense suspensions via shear reversal

Presentation Date and Time
October 15, 2024 (Tuesday) 11:30

Track / Room
Track 3 / Waterloo 5

Authors (Click on name to view author profile)

  1. Pappalardo, Ryan (Case Western Reserve University, Department of Chemistry)
  2. Orsi, Michel (CUNY City College of New York, Levich Institute)
  3. Singh, Abhinendra (Case Western Reserve University, Macromolecular Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Ryan Pappalardo1, Michel Orsi2 and Abhinendra Singh3
1Department of Chemistry, Case Western Reserve University, Cleveland, OH; 2Levich Institute, CUNY City College of New York, New York, NY 10031; 3Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106

Speaker / Presenter 
Singh, Abhinendra

Keywords
computational methods; colloids; dense systems; networks; particles; suspensions

Text of Abstract
Dense suspensions are dispersions of small particles in a Newtonian solvent that are ubiquitous in nature and industry. The presence of various surface interactions and particle properties such as size, roughness, interfacial chemistry, and shape manifests itself as various non-Newtonian rheological features including but not limited to yielding, shear thinning, shear thickening, and jamming. In this work, we use a simulation tool LF-DEM that combines lubrication flow (LF) with discrete element method (DEM) to simulate non-Brownian inertialess neutrally buoyant particles dispersed in a Newtonian suspending fluid. We include short-range electrostatic repulsion and van der Waals attraction together with lubrication and contact friction. The yield stress is observed at low-stress states for strong enough attraction, which increases with particle loading. To elucidate the role of different types of interactions, we employ shear reversal under constant shear stress. In the absence of attractive forces, frictional contacts break down under shear reversal. At a high enough strength of attraction, attractive forces help stabilize the frictional forces under shear reversal. We also find distinct network features at yielding compared to the shear-thickened or jammed states.