Robert D. Schroll

  Physics Department Physics Department James Franck Institute James Franck Institute University of Chicago University of Chicago

I am a graduate student in the Department of Physics and the James Franck Institute at the University of Chicago. I plan to defend my thesis in early 2009. My CV is available in PDF format.

I am fascinated by the fact that the relatively simple laws of classical physics can give rise to the complex behavior that we see in the everyday world. This has led to the fields of soft condensed matter and non-linear physics. Specifically, I have been conducting research on fluid dynamics. I am particularly interested in interfaces between fluids and their dynamics.

Current Research

For my thesis, I am working with Wendy Zhang at the University of Chicago. We have investigated several fluid systems.

Impact of a Viscous Drop

Recent research from the Nagel group at the University of Chicago has show that air plays a critical role in the splashing of a liquid drop impacting a solid surface. (See PRL 94, 184505, and PRE 75, 056316.) This effect was unexpected and is still not well understood.

Profiles of a drop during impact To understand how splashing occurs, we must first understand the process of a drop impacting on a solid surface. With this goal, we are simulating the impact of a viscous drop onto a dry solid substrate, in collaboration with Stephane Zaleski and Christophe Josserand of the Université Pierre et Marie Curie in Paris. I have led the effort to validate the simulations against themselves and experiments, as well as our analysis of the data. We have found that the size and shape of the drop after impact are set by the growth of a viscous boundary layer from the substrate. A paper on this work is currently in prepartion.

Behavior of a Complex Fluid near a Phase Transition

We have worked on two projects in collaboration with Jean-Pierre Delville of the Université Bordeaux. He has developed a micellar fluid which is very near a phase transition at room temperature. This fluid can separate into two phases, and the interface between them, which is very weak, can be probed with a laser.

Profiles of hump shapeIn the first project, we showed that laser not only acts on the interface, but it also provides a driving force on the bulk fluid itself. Because the fluid is near a second-order phase transition, it experiences fluctuations. These fluctuations scatter the laser light, transmitting momentum into the fluid and driving the flow. I calculated the momentum transfer to the fluid by the scattering and developed a model for the resultant flow. We visualized the flow by the way that it distorted the interface between the two phases, and the model and experiments showed excellent agreement. This work was published in PRL 98, 133601.

Light funneled into the jetIn the second project, we examined the effect of the laser directly on the interface. In a certain regime, the laser can create a jet of one phase protruding into the other. The formation and disappearance of this jet displays a hysteretic behavior. I developed a simple ray-optics model which explained how total internal reflection of laser light could hold the jet open against surface tension. We showd that this model explains qualitative features of the jet, including the hysteresis, but, because of its simplicity, it cannot make quantitative predictions. We published this work in Eur. Phys. J E 26, 405.

Past Research

During my first year at Chicago, I worked on a Physics 335 project under Henry Frisch. This project investigated the feasibility of a new type of time-of-flight detector for use at collider detectors, like those at Fermilab and LHC. I produced a final report on this work for the class.

As an undergraduate at the University of Maryland, I did some work for Raj Roy. Raj's group works on non-linear optics, but I spent my time playing with computer-generated holograms. Apparently, this work has been of some use after I left.

Even before that, I worked for a summer with Ted Einstein, analyzing data taken by J.J. Métois of atomic steps on silicon surfaces. The riveting report will be posted if I ever find it.

Publications

In preparation

Press

Our work on light-driven flow attracted a bit of attention in the press. It was written up in Photonics Spectra [7.6 MB PDF]. Summaries appeared on quite a few websites, including

Contact

The best way to reach me is usually by email: rschroll@uchicago.edu. At the University of Chicago, my phone number is 773 702-0946, and my mailing address is:

The James Franck Institute Center for Integrative Science University of Chicago 929 E. 57th St., CIS E208 Chicago, IL 60637

Various and Sundry Links

I play trumpet in the University's Jazz X-tet. A few recordings of the group can be found here.

I also play assorted brass instruments in the Pep Band.

When there's no snow on the ground, I play in the graduate student softball league. You can check out my batting stats.

When I visted Jean-Pierre Delville in Bordeaux, I took a bunch of pictures.