Paper Number
CS46                         My Program 

Session
Colloidal Suspensions and Granular Materials

Title
From sedimentation to suspension: Critical strain as a predictor of particle resuspension under shear

Presentation Date and Time
October 22, 2025 (Wednesday) 4:25

Track / Room
Track 1 / Sweeney Ballroom A

Authors (Click on name to view author profile)

  1. Mahmoudian, Mohammadreza (University of Illinois at Chicago, Mechanical engineering)
  2. Rogers, Simon A. (University of Illinois Urbana-Champaign, Chemical and Biomolecular Engineering)
  3. Mirbod, Parisa (University of Illinois at Chicago, Mechanical engineering)

Author and Affiliation Lines (in printed abstract book)
Mohammadreza Mahmoudian1, Simon A. Rogers2 and Parisa Mirbod1
1Mechanical engineering, University of Illinois at Chicago, Chicago, IL 60607; 2Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Mahmoudian, Mohammadreza

Keywords
experimental methods; theoretical methods; applied rheology; granular materials; particualte systems; rheometry; suspensions

Text of Abstract
The resuspension of sedimented particles in a viscous fluid plays a critical role in environmental and industrial processes—from riverbed erosion to blood flow and industrial mixing. While prior studies have focused on turbulence-dominated regimes, less is understood about particle dynamics and related models in laminar flows where gravitational and shear forces are comparable. These conditions are common in riverbeds, biomedical flows, and seismic-induced sediment transport, where particle mobilization shows thresholds, hysteresis, and memory effects. In this study, we investigate the resuspension of dense, non-Brownian spherical particles in a Newtonian fluid subjected to both steady and oscillatory shear flows. Using bulk rheology and in situ rheo-microscopy, we examine a range of particle volume fractions (? = 0.30–0.55) and identify shear strain as the primary control parameter for resuspension. Our results reveal a strain-driven transition from a stable sediment bed to a homogeneously suspended state, which is mediated by effective particle-particle collisions and collective motion, and it is independent of the applied shear rate. We further introduce a theoretical model that correlates critical strain with particle concentration, enabling the prediction of resuspension thresholds under different shear conditions. Based on this, we make universal state diagrams that classify sedimented, resuspension, and full suspension regimes under both steady and oscillatory shear flow. These findings provide a new framework to understand and control resuspension dynamics in low-Reynolds-number flows, with implications for environmental, biomedical, and functional materials.