When:
Thursday, December 15, 2016
2:00 PM - 3:00 PM CT
Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it
Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students
Contact:
Pamela Villalovoz
(847) 491-3644
Group: Physics and Astronomy Complex Systems Seminars
Category: Academic
Title: Mind the Gap: A new Kind of Fingering Instability in Colloidal Rollers
Speaker: Michelle Driscoll, New York University
Abstract: When colloidal particles are rotated adjacent to nearby floor, strong advective flows are generated around them, even quite far away. When a group of these microrollers is driven, the strong hydrodynamic coupling between particles leads to formation of new structures: an initially uniform front of microrollers evolves first into a shock-like structure, which then quickly becomes unstable, emitting fingers of a well-defined wavelength. Our experiments and simulations confirm that this instability is quite different than typical fingering instabilities, where size scale selection is a consequence of competing stresses. Here, the instability arises only due to hydrodynamic interactions, and it is controlled by a single geometric parameter, the particle-floor gap. We have developed a simplified continuum model that reproduces the instability behavior. This model confirms that this instability is a direct consequence of the inward flows created by the interactions between the particles and the nearby solid surface.
Host: Adilson Motter
Keywords: Physics, Astronomy, Complex Systems