PHYSICAL MATHEMATICS SEMINAR


TOPIC:		ELECTROHYDRODYNAMIC AND FERROHYDRODYNAMIC INTERACTIONS
		WITH ELECTRICALLY CHARGED, DIELECTRIC, AND MAGNETIZABLE
		LIQUIDS


SPEAKER:	MARKUS ZAHN
		Department of Electrical Engineering and Computer Science
		Laboratory for Electromagnetic and Electronic Systems
		Massachusetts Institute of Technology


ABSTRACT:

Continuum electromechanics of electrohydrodynamic interactions
between charged and polarizable dielectric liquids and ferrohydrodynamic
interactions in magnetic liquids (ferrofluids) will be described with many
videotaped demonstrations of simple experiments including Coulombic force
on a surface charged dielectric liquid to act as a pump; an electric field
to cause rotation of an insulating solid cylinder within a more conducting
liquid (von Quincke's rotor); spontaneous high voltage generation from
self-excited electrostatic induction machines (Lord Kelvin's dynamo using
falling water droplets); self-excited dc and ac power generation and
spontaneous rotor oscillations using commutator machines; interfacial
fluid convection cells driven by interfacial surface charge; fluid rise
due to electrical polarization forces; electrostatic control of fluid jet
profiles; electric field stabilization of the Rayleigh-Taylor instability
of a more dense fluid over a less fluid; coupled electric field convective
instability between a charged liquid jet and a fixed spring; ferrofluid
behavior in magnetic fields; ferrofluid and dielectric fluid labyrinth
instability in imposed uniform magnetic or electric  fields; magnetic
field stabilization of the Saffman-Taylor pusher fluid instability when a
less viscous fluid pushes a more viscous ferrofluid; ferrofluid flow
reversals, nonlinear flow response, and magnetic field dependent increase
and decrease in effective viscosity in AC and traveling wave magnetic
fields including zero and negative effective viscosities.


DATE:		TUESDAY, SEPTEMBER 25, 2001

TIME:		2:30 PM

LOCATION:	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