Computations in Science Seminars

Wednesdays at KPTC 206, unless otherwise specified

The Kersten Physics Teaching Center is on the corner of 57th Street and Ellis Avenue.

Discussion over bag-lunch at 12:15 PM. Talk starts at 12:30 PM.

INFORMATION FOR SPEAKERS

Upcoming seminars

Previous seminars

This seminar series is organized by David Biron, email address, Wendy Zhang, email address, and Leo Kadanoff, email address.

 A photo of M51 Galaxy

Whirlpool Galaxy M51
December 2, 2009 (#)
Ryan Hayward, University of Massachusetts, Amherst
e-mail: email address, Faculty contact: Ka Yee Lee, email address
An elastic creasing instability of soft polymer surfaces
Soft solids placed under compressive stress can undergo a surface buckling instability leading to formation of sharply-folded creases on their free surfaces. We study a particular example of this instability that occurs upon swelling of crosslinked polymer networks on rigid substrates; when placed in contact with solvent, they are subjected to compressive swelling stresses due to the constraint against lateral expansion imposed by the substrate. We have studied a series of surface-attached hydrogels and found the conditions for instability to be rather insensitive to material properties or layer thickness, in accord with simple predictions. Using temperature-responsive gels, we seek to elucidate the mechanism of crease formation and growth, as well as the evolution of crease structures. Finally, we take advantage of this instability as a way to create dynamic polymer surfaces with reconfigurable chemical patterns.
December 9, 2009 (#)
Benny Davidovitch, University of Massachusetts, Amherst
e-mail: email address, Faculty contact: Ka Yee Lee, email address
Instabilities and morphological phases of stressed elastic membranes
Crumpled papers, wrinkled skins, and buckled plant leaves are few familiar examples of the rich variety of patterns that elastic membranes may exhibit under quite featureless constraints. One may ask: Does a morphological "phase space" exist, according to which the many possible membrane patterns are classified? What are the relevant parameters that determine whether a distribution of forces and constraints gives rise to a smooth shape (e.g. periodic wrinkles) or to an irregular one, characterized by localized ridges and vertices (e.g. crumpled sheets)? In this talk I will address these questions, by focusing on an elementary case: highly-symmetric membrane (homogenous, isotropic, of rectangular shape) that is buckled under uniaxial compression and is subjected to a uniform tension in the orthogonal direction. I will show that a surprisingly rich "phase diagram" of distinct morphologies is spanned by a pair of dimensionless parameters that encapsulate the relevant mechanical conditions and geometric constraints. In particular, a novel series of "period fissioning" instabilities gives rise to a new type of wrinkling cascade when the tension is sufficiently large. This instability mechanism is shown to underlie a recently-discovered phenomenon: A smooth cascade of wrinkles, in uniaxialy-compressed ultrathin membranes, floating on liquid and subject to tension and geometric frustration due to strong capillary forces.
January 13, 2010
Tom Solomon, Bucknell University
e-mail: email address, Faculty contact: Wendy Zhang, email address
January 20, 2010
Michael Foote, University of Chicago
e-mail: email address, Faculty contact: Leo Kadanoff, email address
January 26, 2010 (JFI seminar)
Piotr Szymczak, Warsaw University
e-mail: email address, Faculty contact: Leo Kadanoff, email address
January 27, 2010
Shreyas Mandre, Harvard University
e-mail: email address, Faculty contact: Wendy Zhang, email address
February 3, 2010
Heinrich Jaeger, University of Chicago
e-mail: email address
February 10, 2010
Steve Berry, University of Chicago
e-mail: email address
February 17, 2010
Juan Restrepo, University of Arizona
e-mail: email address, Faculty contact: Ridgway Scott, email address
February 24, 2010
Mike Wilde, Argonne National Laboratory
e-mail: email address, Faculty contact: David Biron, email address
March 3, 2010
Daniel Rothman, Massachusetts Institute of Technology
e-mail: email address, Faculty contact: Leo Kadanoff, email address
March 10, 2010
Chris Myers, Cornell University
e-mail: email address, Faculty contact: Leo Kadanoff, email address
March 17, 2010 (during March meeting)
(open date)
March 24, 2010 (^)
(open date)
March 31, 2010 (^)
(open date)
April 7, 2010 (#)
David Chandler, University of California, Berkeley
e-mail: email address, Faculty contact: Leo Kadanoff, email address
April 14, 2010 (#)
Itai Cohen, Cornell University
e-mail: email address, Faculty contact: Wendy Zhang, email address
April 21, 2010 (#)
(open date)
April 28, 2010 (#)
(open date)
May 5, 2010
Daan Frenkel, Trinity College, UK
e-mail: email address, Faculty contact: Tom Witten, email address
May 12, 2010
(open date)
May 19, 2010
Mark Goulian, University of Pennsylvania
e-mail: email address, Faculty contact: David Biron, email address
May 26, 2010
(open date)
June 2, 2010
(open date)
June 9, 2010
(open date)
June 16, 2010
(open date)

(&) : When Wendy Zhang is unavailable for the seminar.

(^) : When Leo Kadanoff is unavailable for the seminar.

(#) : When David Biron is unavailable for the seminar.

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