Jamming, Two-Fluid Behavior, and “Self-Filtration” in Concentrated Particulate Suspensions

Jamming, two-fluid behavior, and "self-filtration" in concentrated particulate suspensions.

We study the flow of model hard-sphere colloidal suspensions at high volume fraction Phi driven through a constriction by a pressure gradient. Above a particle-size dependent limit Phi(0), direct microscopic observations demonstrate jamming and unjamming-conversion of fluid to solid and vice versa-during flow. We show that such a jamming flow produces a reduction in colloid concentration Phi(x)...

Particle-pressure-induced self-filtration in concentrated suspensions.

Gravity-driven flow of concentrated suspensions (solid volume fraction ϕ>0.50) of non-brownian spherical particles through a channel contraction at low Reynolds number is studied experimentally. The abrupt change in the flow area at the contraction forms distinct shear-rate regions having different fluid pressures, which are related to the concept of particle pressure. A model involving particl...

DESIGN AND TESTING OF AN EXPERIMENT TO MEASURE SELF-FILTRATION IN PARTICULATE SUSPENSIONS by Mattias

An experiment for measuring self-filtration in terms of change in volume fraction downstream of a constriction compared to volume fraction upstream of said constriction was designed and tested. The user has the ability to control a variety of parameters including constriction geometry, flow rate, and initial volume fraction in order to evaluate their impact on downstream volume fraction. The re...

Local transient rheological behavior of concentrated suspensions

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming.

Shear thickening is a type of non-Newtonian behavior in which the stress required to shear a fluid increases faster than linearly with shear rate. Many concentrated suspensions of particles exhibit an especially dramatic version, known as Discontinuous Shear Thickening (DST), in which the stress suddenly jumps with increasing shear rate and produces solid-like behavior. The best known example o...