Annual European Rheology Conference (AERC 2022)

Rheology and fluid mechanics of concentrated suspensions

Jeff Morris
CUNY City College of New York
Levich Institute and Department of Chemical Engineering

Suspensions display a remarkably rich range of behavior.  This is particularly true under conditions where the particles are concentrated, which rather arbitrarily we may say that take as particle volume fraction f > 0.3. This includes rheological properties that vary extremely rapidly with shear rate, strong normal stresses, and the two-phase flow phenomenon of shear-induced migration.   Because suspensions of spherical particles immersed in Newtonian liquid  are simple and readily characterized, they provide the ideal ground for determining the fundamental basis for these behaviors.  Considering experiment, discrete-particle simulations, and theory, I will trace efforts to understand nonlinear rheology in suspensions of “near-hard-sphere” suspensions, focusing on two topics: 1) particle pressure, including both its microstructural basis and impact on migration, and 2) DST and shear jamming in very dense suspensions.   As both phenomena can be linked to microstructural features I will also discuss methods to describe, and in limited cases predict, the microstructure, from pair-particle correlations to percolated network structures.