Northwestern Events Calendar


Complex Systems Seminar: Professor Karen Daniels: Fingers, fractals, and flow in liquid metals

When: Thursday, November 19, 2020
2:00 PM - 3:30 PM Central

Where: Online

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Cristian Pennington   (847) 491-3645

Group: Physics and Astronomy Complex Systems Seminars

Category: Academic


A droplet of pure water placed on a clean glass surface will spread axisymmetrically, and a droplet of mercury will bead up into a spherical droplet. In both cases, the droplet is minimizing its surface energy -- creating an object with a minimized surface area -- and there is nothing to break the symmetry. Remarkably, droplets of the room-temperature liquid gallium-indium (EGaIn), which like all metals have an enormous surface tension, can nonetheless undergo fingering instabilities in the presence of an oxidizing voltage. I will describe how this oxide acts like a reversible surfactant, generating fingering instabilities, tip-splitting, and even fractals through Marangoni instabilities. Remarkably, we find that EGaIn droplets placed in an electrolyte under an applied voltage can achieve near-zero surface tension. This effect can in turn be used to suppress the Rayleigh-Plateau instability in falling streams. Quantitative control of these effects provides a new route for the development of reconfigurable electronic, electromagnetic, and optical devices that take advantage of the metallic properties of liquid metals.

Professor Karen Daniels, North Carolina State University

Host: Michelle Driscoll

Keywords: Physics, Astronomy, Complex Systems

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