Fall 2016

Seminars are held on Mondays from 2:30 - 3:30PM in Cullimore Hall, Room 611, unless noted otherwise. For questions about the seminar schedule, please contact David Shirokoff.


Date: October 17, 2016

Speaker: Kyongmin Yeo
IBM T.J. Watson Research Center,

Academic Profile

Title: "Collective Motions in Active Suspensions of Micro-Rotors"

Abstract:

Soft active matter, which consists of a bath of “active” agents interacting with each other, has attracted great attention in the last decade across diverse areas, most notably biophysics, material sciences, and fluid mechanics. One of the distinguishing features of soft active matters is the capability of converting the energy supplied to the system by the active agents into mechanical work. In this talk, I will present some of our recent findings on the collective motions in a batch of active rotors suspended in viscous liquid, where the rotational kinetic energy supplied by the spontaneous rotation of the particles are converted into translational kinetic energy through hydrodynamic interactions. The batch of micro-rotors consists of 50:50 mixture of opposite spin rotors. It is found that the suspensions of active rotors develop collective motions, of which mode depends on the volume fraction of the rotors. At low volume fraction, the dominant mode is translation of the opposite-spin rotors, which changes to rotating crystals at higher volume fractions. Eventually, above a critical volume fraction, crystals of random spin distribution emerge, which leads to a sharp drop in the energy conversion rate. It is found that the phase boundary changes when passive particles are introduced into the system. Because of the collective motions of active rotors, the mobility of the passive particles can increase dramatically at high volume fractions.