Woodrow L. Shew

Experiments in statistical and nonlinear physics, fluid dynamics, and biological networks

NIH/NIMH
Bldg 35 Rm 3A-202
35 Convent Dr
Bethesda, MD, USA 20892
email: sheww@mail.nih.gov
phone: 301-402-6947
a side project
of mine:

News


Collaborations


Publications


Ongoing Research

Smart ParticlesARTICLES: PRL RSI
We have developed flow tracing particles with on-board measurements (e.g. acceleration, temperature) and wireless communications systems (RF). These particles may be used to make Lagrangian measurements in a broad range of laboratory and natural fluid flows. We have made quantitative measurements heat Lagrangian transport of thermal plumes in Rayleigh-Benard convection. (with Y. Gasteuil, M. Gibert, and J.-F. Pinton at ENS Lyon)
Neuronal Networks
Using a two-photon microscope and multi-electrode arrays we study patterns of activity in neuronal networks in rat cortex. Our aim is to understand the basis of neuronal avalanches in large neuronal networks with single cell resolution. (with D. Plenz at National Institutes of Health)
3-D Imaging of Neurons
We are developing a novel two-photon microscopy technique for imaging three-dimensional groups of neurons simultaneously. The project is a collaboration between University of Maryland and National Institutes of Health with Rarjarshi Roy and Dietmar Plenz

Past Research

BubblesARTICLES: PRL JFM JSTAT
Continuous ultrasound and high speed cameras are used to measure the three dimensional trajectory of air bubbles in water. The ultrasound method provides direct and very sensitive velocity measurements. We deduce quantitative measurementsof the forces on the bubbles from the peculiar zigzagging and spiraling bubble trajectories. We have developed a simple dynamical model for these motions based on our measurements. We have also explored viscoelastic effects on these dynamics with bubbles rising in non-Newtonian fluids. (with J.-F. Pinton at ENS Lyon)
Experimental Model of
Earth's Core
ARTICLES: PEPI My PhD
The motion of the molten iron of Earth's outer core was modelled with a 60 cm diameter, rapidly rotating, spherical convection experiment. The titanium vessel contained 100 liters of molten sodium and rotated at rotation rates up to 30 RPS and sustained up to 5 kW of heat transfer. Our results allowed us to estimate the size of convective velocities, time and length scales, ohmic dissipation, as well as the Rayleigh number for the Earth's outer core. (with D. P. Lathrop at UMD)
Magneto-turbulenceARTICLES: PEPI
Molten sodium was driven into a highly turbulent state in the presence of large magnetic fields (up to 0.2 T). As the applied magnetic field is increased, Lorentz forces become large enough to significantly suppress the turbulence. For large enough magnetic fields, instabilities arise in the interactions between the fluid flow and the magnetic field, exhibiting regular patterns in the induced magnetic field. These instabilities may be a laboratory manifestation of the magneto-rotational instability. (with D. R. Sisan & D. P. Lathrop at UMD)
Coupled OscillatorsARTICLES: AJP
An experimental array of 10 coupled pendulums with sinusoidal forcing was used to explore the control of chaos in spatially extended systems. It was found that the system behaved chaotically when all the pendulums were identical and could be pushed into a periodic state by randomly adjusting their lengths; adding disorder tames the chaos. (with J. F. Lindner at COW)