Fall 2007

Sept 20
Speaker:  Daniel Blair, Georgetown University
Title:  Colloids in action: Microscopic insights into
           clogging and jamming

Suspensions of colloidal particles are astounding model systems used  to
study a variety of fundamentally important problems in soft matter
physics. The versatility of colloids is due in large part to the
increasing sophistication of their synthesis, and the relative  physical
simplicity of their interactions. This talk will discuss  recent
experimental results on two soft-matter topics that utilize  colloidal
particles; clogging during flow and jamming in glasses.

I will first present results from microfluidic studies of clogging in
model porous media. By using simple imaging techniques, and a minimal
geometric model, I will describe the physical origins of clogging in
microfluidic devices. These results demonstrate that the aggregation  of
micron sized particles, in a low Reynolds number flow, is  dominated by
single particle interactions. In the second half of the  talk, I will
discuss the microscopic response of colloidal glasses to  a
macroscopically applied compressive stress. Using time resolved  laser
scanning confocal microscopy, I identify and track the motion  of
thousands of colloidal particles in real space over very long  times.
With this technique, and ideas garnered from metallic glasses,  the
complete local strain tensor for each particle is determined. I  will
demonstrate that highly localized, correlated shear and  compression
transformations are necessary for colloidal glasses to  approach a
maximally jammed state.

Sept 27
Speaker: Samuel Zambrano,
Title:  Safe sets for horseshoe maps

Speaker 2:  TBA

Oct 4
Speaker:  Shmuel Fishman, Technion
Title: Anderson Localization for the Nonlinear Schroedinger
             Equation (NLS): results and puzzles.

Abstract: The NLS is relevant for the explorations of Bose-Einstein
Condensates and for Nonlinear Classical Optics. A natural question is
whether Anderson Localization survives the effect of nonlinearities.
Relevant experimental, numerical, heuristic and rigorous results will be
reviewed. Some our preliminary results (in collaboration with A Soffer
and Y. Krivolapov), obtained in the framework of perturbation theory
will be presented.

Oct 11 (n)

Oct 18
Speaker:  Visiting Graduate Student

Speaker 2:  TBA

Oct 25 (n)

Nov 1

Nov 8
BURGERS symposium - no seminar

Nov 15
Pre DFD seminars

Nov 22
Thanksgiving -  no seminar

Nov 29
Speaker:  Gregg Lois, Yale University
Title:  TBA

Dec 6
Speaker:  Tom Wanner, George Mason University


Feb 7
Speaker:  Dan Goldman, Georgia Tech

Feb 14

Feb 21
Speaker:  Leslie Smith, Univ of Wisconsin
Title:  TBA

Feb 28

Mar 6

Mar 13
No seminar - APS March meeting

Mar 20
No seminar - Spring break

Mar 27 (n)

Apr 3  (n)

Apr 10

Apr 17 (n)

Apr 24

May 1

May 8

Sept 6
Speaker: Tom Solomon, Bucknell University
Title:  Fronts and patterns in advection-reaction-diffusion
Host:  Dan Lathrop/Matthew Paoletti