Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session B28: Flow and Structure in Dense SuspensionsInvited
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Sponsoring Units: DSOFT Chair: Michelle Driscoll, Northwestern University Room: 405-407 |
Monday, March 2, 2020 11:15AM - 11:51AM |
B28.00001: Flow of concentrated and highly polydisperse emulsions Invited Speaker: Eric Weeks We study experiments and simulations of highly polydisperse emulsions under shear flow. By highly polydisperse, we mean with the largest droplet diameters being as much as ten times the smallest diameters. We're studying how to best define and quantify non-affine motion in these highly polydisperse samples -- motion where droplets move with displacements distinctly different from their neighbors, or from the overall imposed shear flow. The largest droplets typically move affinely, as if they are in a simple effective fluid formed by the other droplets. In contrast, the smallest droplets often move non-affinely. Additionally, we quantify how the non-affine motion diminishes as a function of droplet size. Our main conclusion is that highly polydisperse samples behave qualitatively differently than weakly polydisperse samples. |
Monday, March 2, 2020 11:51AM - 12:27PM |
B28.00002: Fingering in dense suspensions Invited Speaker: Sungyon Lee We experimentally inject silicone oil into the mixture of oil and non-colloidal particles inside a Hele-Shaw cell, to investigate the connection between miscible fingering and the flow structure that develops inside the dense suspension. Previous studies with pure fluids have demonstrated that the onset of miscible fingering coincides with the transition from a smooth tongue-like structure to a sharp front between invading and defending fluids inside the thin gap. Our current experiments with suspensions reveal the same general behavior at the onset of miscible fingering, which we capture qualitatively using a continuum model. However, beyond the onset, we observe distinctly different morphologies of miscible fingering, which depend on the ratio of the gap thickness to particle diameter. We present the new quantitative measurements that highlight these differences and discuss how the wall confinement may alter the particle dynamics and the resultant fingering patterns. |
Monday, March 2, 2020 12:27PM - 1:03PM |
B28.00003: The rheology of chocolate making Invited Speaker: Wilson Poon The mixing of a powder of 10- to 50-μm primary particles into a liquid to form a dispersion with the highest possible solid content is a common industrial operation. Building on recent advances in the rheology of such “granular dispersions,” we study a paradigmatic example of such powder incorporation: the conching of chocolate, in which a homogeneous, flowing suspension is prepared from an inhomogeneous mixture of particulates, triglyceride oil, and dispersants. Studying the rheology of a simplified formulation, we find that the input of mechanical energy and staged addition of surfactants combine to effect a considerable shift in the frictional jamming volume fraction of the system, thus increasing the maximum flowable solid content. We discuss the possible microscopic origins of this shift, and suggest that chocolate conching exemplifies a ubiquitous class of powder–liquid mixing. |
Monday, March 2, 2020 1:03PM - 1:39PM |
B28.00004: Suspensions of non-Brownian particles in complex fluids: Rheology,
microstructure and fluid mechanics Invited Speaker: Sarah Hormozi Suspensions of non-Brownian particles in complex fluids (hereafter |
Monday, March 2, 2020 1:39PM - 2:15PM |
B28.00005: Force networks in shear thickening suspension Invited Speaker: Jeffrey F Morris From simulations shown to capture primary features of the shear thickening |
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