SPECIAL PHYSICAL MATHEMATICS SEMINAR



TOPIC: 	FILAMENTS IN FLUIDS: FLUTTERING FLAGS, 
	FISHES AND BRIDGES



SPEAKER:	MEDERIC ARGENTINA
		Division of Engineering and Applied Sciences
		Harvard University


ABSTRACT:

We give an explanation for the onset of wind-induced flutter in a flag. 
Our theory accounts for the various physical mechanisms at work: 
the finite length and the small but finite bending stiffness of the flag, 
the unsteadiness of the flow, the added mass effect and vortex 
shedding from the trailing edge. Our analysis allows us to predict a 
critical speed for the onset of flapping as well as the frequency of flapping. 
We find that in a particular limit corresponding to a low-density fluid 
flowing over a soft high-density flag, the flapping instability is akin to 
a resonance between the mode of oscillation of a rigid pivoted airfoil in a 
flow and a hinged-free elastic filament vibrating in its lowest mode. Our 
model is then adapted in order to provide insights on the problem of fish 
locomotion.	


FRIDAY, APRIL 9, 2004
2:30 pm
Building 2, Room 338

Refreshments will be served at 3:30 PM in Room 2-349


Massachusetts Institute of Technology, Department of Mathematics
Cambridge, MA  02139