Levich Institute Seminar Announcement, 11/11/2014
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Eric Brown
Department of Mechanical and Materials Science
"Discontinuous Shear Thickening and Related Phenomena in Concentrated Suspensions "
Concentrated suspensions of hard particles such as cornstarch in water exhibit Discontinuous Shear Thickening, in which an increasing shear rate drives a transition from liquid- to solid-like mechanical behavior. In steady-state shear this phenomena is a result of a dynamic version of jamming in which forces are transmitted between boundaries along particle contact networks that repeatedly form and break up. Several dynamic phenomena observed in such suspensions have long been assumed to be a consequence of this shear thickening, but cannot be explained as a direct result of shear thickening; for example a strong impact response which allows a person to run on the fluid surface. We perform experiments in which a concentrated suspension is subjected to transient impact. We find that the strong impact response is due a short-lived jammed contact network spanning to the boundaries. The delay time required for this dynamically jammed region to propagate to the boundary and the resulting ability to support loads like a solid can explain several of the dynamic phenomena observed in these fluids.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
Eric Brown is an Assistant Professor in the Department of Mechanical Engineering and Materials Science at Yale University. He graduated with a B. S. in Physics from Harvey Mudd College in 2002. He earned his Ph. D. in Physics from the University of California at Santa Barbara in 2007 for his work in turbulent Rayleigh-Benard convection under the guidance of Guenter Ahlers. He was a Postdoctoral Scholar in The James Franck Institute at the University of Chicago working for Heinrich Jaeger.