Computations in Science Seminars
Aug 2015
5
Wed 12:15
Radha Ramachandran, Eve Tulbert, University of Chicago, Freedom Games
e-mail:
Organizer: Kim Weirich ()
'Creating a learning ecosystem for k-12 students'

Planet Lab is a network for hands-on STEM, SCIENCE, TECHNOLOGY, ENGINEERING AND MEDICINE exploration and learning. Radha Ramachandran (Physics PhD 2014, Science Education and Outreach Coordinator MRSEC & RDCEP) and Eve Tulbert (literacy and learning researcher) will describe how they decided to co-found an educational technology start-up dedicated to expanding opportunities for STEM education and engagement. In the first part of the talk, Ramachandran and Tulbert will describe the technology start-up process. Then, they will describe the current research around learning in the concept called "STEM Ecosystems," and discuss ideas with the group for creating learning pathways for K-12 students.

Aug 2015
12
Wed 12:15
Stephane Perrard, University of Chicago
e-mail:
Host: William Irvine ()
Organizer: Sayantan Majumdar ()
Structure in turbulent flows

Is turbulence really scale invariant ? This assumption was already used in the 40’s by Kolmogorov to predict the repartition of energy through scales in a turbulent flow. Even if the first order of such a theory has been observed in many situations, it fails to predict the typical fluctuations of velocity observed in real experimental conditions. This phenonemon of scale invariance break down is often called “intermittency” and it is somehow related to the existence of structures of preferred size. Following these structures and the associated dissipation as a function of time is an experimental challenge, as they travel neither with the individual fluid particles nor with the averaged mean flow.

An insight can however be obtained in zero mean flow experiments, in which all the fluctuations are caught in a closed box. By accelerating a square grid downward in a water tank, we generate an array of wakes that induces a 3 dimensional turbulent flow. After the impulse excitation (about 100ms), a decay of the turbulent flow due to dissipation at small scales is observed. The entire decay process lasts for hours, the dissipation scale rising up through scales with time. Using an experimental trick, I will show that it is possible to follow and characterized this turbulent decay process through several order of magnitude in time using one single movie.

In a second part of my talk, I will briefly introduce some possible path of my future research. I will present in particular two experiments, one focusing on the interaction between a vortex ring and a turbulent background flow, the other on the dynamics of vortex filaments in a sheared boundary layer.

Aug 2015
19
Wed 12:15
Sayantan Majumdar, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Organizer: Shiladitya Banerjee ()
Dynamic jamming under extensional flow in a dense particulate suspension

It requires a lot of force to quickly pull out an object immersed in a bath of dense granular suspension like corn starch in water To understand such striking force response under extensional flow, we experimentally measure the normal force required for pulling out a rod vertically from the suspension at a controlled velocity. We observe that for slow velocities the force response is similar to that of highly viscous fluids but above a threshold velocity the force show a diverging behavior soon after the initial viscous-like response. We use non-optical methods like X-ray and fast ultrasound imaging to map out the local velocity profiles inside the optically opaque suspension during extensional flow. These measurements clearly show that under rapid extension, there is a growing jammed region inside the suspension that interacts with the rigid boundaries of the container giving rise to the observed force divergence. Our findings suggest that under rapid extension the force repose in dense granular suspensions is very similar to impact activated solidification even though the concept of jamming under extension is highly non-intuitive.

Aug 2015
26
Wed 12:15
Kim Weirich, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Organizer: Ivo Peters ()
Sep 2015
30
Wed 12:15
Sarah Cobey, University of Chicago
e-mail:
Host: Michael Rust ()
Oct 2015
7
Wed 12:15
Zvonimir Dogic, Brandeis University
e-mail:
Host: William Irvine ()
Oct 2015
14
Wed 12:15
Michael Oppenheimer, Princeton
e-mail:
Host: Leo Kadanoff ()
Oct 2015
21
Wed 12:15
Kathleen Stebe, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Oct 2015
28
Wed 12:15
Tom Lubensky, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Nov 2015
4
Wed 12:15
Eric Siggia, Rockefeller University
e-mail:
Host: Greg Voth
Nov 2015
11
Wed 12:15
David Schuster, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Nov 2015
18
Wed 12:15
Daniel Rothman, MIT
e-mail:
Host: Leo Kadanoff ()
Earth-System Stability through Geologic Time
Dec 2015
2
Wed 12:15
OPEN
Dec 2015
9
Wed 12:15
Charles Kane, University of Pennsylvania
e-mail:
Host: Leo Kadanoff ()
Dec 2015
16
Wed 12:15
Jeremie Palacci, New York University
e-mail:
Host: William Irvine ()
Jan 2016
5
Tue 4:00 PM
Seth Lloyd, MIT
e-mail:
JFI COLLOQUIUM - ROOM W301 - 4:00 PM
Jan 2016
6
Wed 12:15
Seth Lloyd, MIT
e-mail:
Host: Leo Kadanoff ()
Jan 2016
13
Wed 12:15
Eleni Katifori, University of Pennsylvania
e-mail:
Host: David Biron ()
Jan 2016
20
Wed 12:15
OPEN
Jan 2016
27
Wed 12:15
Jeffrey Harvey, University of Chicago
e-mail:
Host: Daniel Holz ()
Feb 2016
3
Wed 12:15
OPEN
Feb 2016
10
Wed 12:15
Mark Bowick, Syracuse University
e-mail:
Host: William Irvine ()
Feb 2016
17
Wed 12:15
Chris Fang-Yen, University of Pennsylvania
e-mail:
Host: David Biron ()
Feb 2016
24
Wed 12:15
OPEN
Mar 2016
2
Wed 12:15
OPEN
Mar 2016
9
Wed 12:15
John Novembre, University of Chicago
e-mail:
Host: Leo Kadanoff ()
Mar 2016
16
Wed 12:15
Randy H. Ewoldt, University of Illinois Urbana-Champain
e-mail:
Host: Leo P. Kadanoff ()
Mar 2016
30
Wed 12:15
OPEN
Apr 2016
6
Wed 12:15
OPEN
Apr 2016
13
Wed 12:15
OPEN
Apr 2016
20
Wed 12:15
OPEN
Apr 2016
27
Wed 12:15
OPEN
May 2016
4
Wed 12:15
OPEN
May 2016
11
Wed 12:15
OPEN
May 2016
18
Wed 12:15
OPEN
May 2016
25
Wed 12:15
OPEN
Jun 2016
1
Wed 12:15
OPEN
Jun 2016
8
Wed 12:15
OPEN