W. G. Pritchard Lab Seminar: 4:00-5:00 PM, 101 Osmond Laboratory

	            **Tuesday October 14, 2003**
	
Symmetry breaking leads to forward flapping flight

Nicolas Vandenberghe

Applied Math Laboratory
Courant Institute of Mathematical Sciences
New York University

Abstract:

Flapping flight is ubiquitous in nature, yet cilia and flagella, not wings,
prevail in the world of micro-organisms. We discuss this dichotomy. In our 
experiment, a wing, mounted on a shaft and free to move horizontally, is 
flapped up and down. The wing begins to move forward spontaneously as a 
critical frequency is exceeded, indicating that "flapping flight" occurs 
as a symmetry-breaking bifurcation from the state of rest. A dimensionless 
parameter is identified which determines the point of bifurcation, thus 
providing a physical basis for the very different methods of locomotion of
large and small organisms.