Gwynn J. Elfring Ph.D, P.Eng
Assistant Professor | Department of Mechanical Engineering
The University of British Columbia
Abstract: Active particles in complex fluids
Active particles are self-driven objects, biological or otherwise, which convert stored or ambient energy into systematic motion. The motion of small active particles in Newtonian fluids has received considerable attention, with interest ranging from phoretic propulsion to biological locomotion, whereas studies on active bodies immersed in complex fluids are comparatively scarce. A simple model for an active particle considers a sphere with an axisymmetric distribution of slip-velocities on its surface, known as the squirmer model. This model has been helpful in developing insights into the dynamics of both biological swimmers, like Volvox and Opalina, and synthetic self-propelling colloids. In this talk we present a theory for an active squirmer-type particle in a complex fluid, and then discuss the effects of viscoelasticity and shear-thinning rheology in the context of biological locomotion and the propulsion of colloidal Janus particles.
Gwynn Elfring is an Assistant Professor in the Department of Mechanical Engineering and the Institute of Applied Mathematics at the University of British Columbia. His research involves modeling the fluid mechanics of soft matter systems, including cell locomotion and cellular biophysics, the mechanics of (active) suspensions, interfacial and membrane rheology, and non-Newtonian flow physics. In particular, he studies the dynamics of passive and active bodies – from bacteria to Janus particles – in complex and biological fluids. Previously, he completed a Ph.D. at the University of California San Diego under the supervision of Eric Lauga and postdoctoral studies with L. Gary Leal and Todd M. Squires at the University of California Santa Barbara before joining the faculty at UBC in 2013.