University of Minnesota
Aerospace Engineering and Mechanics
Fall 2000 Seminar Series



Twist, kinks, and drag: whirling elastica


Professor Tom Powers

Division of Engineering, Brown University


Abstract

Cellular biophysics provides many examples of flexible elastic filaments rotating in a viscous fluid, from DNA transcription to supercoiling bacterial colonies. Motivated by these problems, we study the torsional stress and steady-shape shape for a rotating rod with a kink, and show theoretically and experimentally how the rod exhibits bistability between extended and folded states. We then consider the whirling instability of a twirling rod without kinks, which illustrates the implications for open rods of White's theorem relating link, twist, and writhe for closed ribbons.


Friday, October 6, 2000
209 Akerman Hall
2:30-3:30 p.m.


Refreshments served after the seminar in 227 Akerman Hall.
Disability accomodations provided upon request.
Contact Kristal Belisle, at (612) 625-8000.