PHYSICAL MATHEMATICS SEMINAR

TOPIC:		FROM FLAPPING FLAGS TO DRIFTING CONTINENTS:  
		DYNAMIC BOUNDARIES AND FLUID INTERACTION.

SPEAKER:	DR. JUN ZHANG
		Courant Institute of Mathematical Sciences
		New York University

ABSTRACT:

Hydrodynamics has typically dealt with the effect on flows of fixed
boundaries such as the rigid walls of a pipe flow or the solid box
containing a convective fluid.  However, interesting phenomena are
expected when hydrodynamic forces are strong enough to modify the shape of
a flow boundary, and the boundary in turn changes the flow.

We investigate here two examples of systems with deformable (movable)
boundaries.  The first experiment, a system akin to the flag-in-the-wind
problem, studies a thin flexible body in a quasi-two-dimensional fluid.  
The system exhibits an interesting bi-stability and the motions can be
related to the undulations of a swimming fish.  In the second example, a
thermally convecting fluid interacts with a freely floating plate,
providing a simple model of a continent floating on the Earth's mantle.  
The experimental results support the theory that the Atlantic Ocean might
have closed and re-opened several times in the past two billion years.

DATE:		TUESDAY, MARCH 28, 2000

TIME:		2:30 PM

LOCATION:	Building 2, Room 338


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


					Massachusetts Institute of Technology
					Department of Mathematics
					Cambridge, MA  02139