PHYSICAL MATHEMATICS SEMINAR

TOPIC:		LIQUID FLOW (DRAINAGE) IN AQUEOUS FOAMS:

SPEAKER:	DR. STEPHAN KOEHLER
		Department of Engineering and Applied Sciences
		Harvard University

ABSTRACT:

The flow of liquid through the interstitial space between the
bubbles of a foam is similar to liquid flow through porous media.  As with
porous media, such as a packed bed of spheres, the observable is the
macroscopic flow rate.  However rather than having a fixed permeability,
the permeability of foams increases with the flux.  This is because unlike
porous media, where the interstitial space is fixed, in foams the bubbles
are deformable and the interstitial space increases with the liquid flux.
Furthermore there is evidence that the boundary condition for the flow may
depend on the surfactant, and the flow velocity may not necessarily be
zero at the liquid/air interface.

I will discuss several types of foam drainage experiments in one
dimension, introduce a simple model and compare predictions with
experimental results for monodisperse foams. Emphasis will be placed on
the dynamics of the liquid volume fraction profile.  I will also discuss
some preliminary results for bidisperse foams, which are composed of
bubbles with two different sizes.


DATE:		TUESDAY, OCTOBER 26, 1999

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