Icicles, washboard road and meandering syrup

This talk will describe three recent experiments on emergent nonlinear patterns in three diverse physical systems. The overall shape and subsequent rippling instability of icicles is an interesting free-boundary growth problem. It has been linked theoretically to similar phenomena in stalactites. We built a machine to grow icicles in the lab and determined the motion of their ripples. Washboard road is the result of the instability of a flat sandy surface under the action of rolling wheels. The rippling of the road, which is a major annoyance to drivers, sets in above a threshold speed and leads to waves which travel down the road. We studied these waves, which have their own interesting dynamics, both in the laboratory and using molecular dynamics simulation. A thread of viscous fluid, like syrup, falling onto a moving belt creates a novel device called a “fluid mechanical sewing machine.” The thread exhibits a rich zoo of states as a function of the belt speed and nozzle height.

Professor and Undergraduate Associate Chair, Department of Physics, University of Toronto.

B.Sc., British Columbia (1981)

M.Sc., British Columbia (1985)

Ph.D., Toronto (1991)

NSERC Postdoctoral Fellow, Santa Barbara (1991-1993)

APUS/SAC Teaching Award, Toronto (2003)

Faculty of Arts & Science Outstanding Teaching Award, Toronto (2004)

Senior Visiting Fellow, The Isaac Newton Institute for Mathematics, Cambridge University (2005).

Visiting Fellow, Clare Hall, Cambridge University (2006). "