From: LARRY KLAES (ljk4_at_msn.com)
Date: Tue Mar 04 2003 - 17:00:21 PST
----- Original Message -----
From: cunews_at_cornell.edu
Sent: Monday, March 03, 2003 3:00 PM
To: CUNEWS-PHYSICAL_SCIENCE-L_at_cornell.edu; CUNEWS-SCIENCE-L_at_cornell.edu
Subject: Cornell News: NSF turbulence grant
Cornell team's high-tech 'snow globe' awarded $1.4 million by NSF to
shed light on turbulent flows
FOR RELEASE: March 3, 2003
Contact: David Brand
Office: 607-255-3651
E-mail: deb27_at_cornell.edu
ITHACA, N.Y. -- Under a black cloth in a small cylinder in the
basement of a Cornell University building, a storm is raging. The
cloth is there to protect the unwary from the centerpiece of the
laboratory, an instrument equipped with a laser beam powerful enough
to harm the retina of the eye in a fraction of a second. A judicious
peek beneath the cloth reveals the tempest: the laser's green light
illuminating a clear cylinder filled with whirling "snowflakes"
suspended in water. What looks like a high-tech snow globe is
actually an apparatus designed to answer one of the great unanswered
questions of physics: How do particles behave in turbulence?
At Cornell's Laboratory of Atomic and Solid State Physics and
Laboratory of Elementary Particle Physics, researchers have been
tracking the paths of the tiny polystyrene "snowflakes" in the
cylinder in an effort to shed light on the behavior of turbulent
flows. But current technology only allows observers to follow a few
particles at a time, making it nearly impossible to gather enough
data to accomplish the task. Now, with a $1.4 million, three-year
grant from the National Science Foundation (NSF), a group of Cornell
physicists and engineers are developing an instrument that will allow
them to track hundreds of particles simultaneously.
With it, they believe they will dramatically advance scientists'
understanding of turbulence -- and, perhaps, even begin to tackle the
long-unsolved problem of predicting how turbulent fluid flows behave.
Turbulence affects how pollutants disperse in air or water, how far
pollen from crops will spread and how fast chemicals mix in
industrial processes. Understanding how warm clouds form in turbulent
air currents could improve the global circulation models that
climatologists use to predict global warming.
"There are a lot of fundamental turbulence questions that can be
attacked with this new technology," says Eberhard Bodenschatz,
professor of physics and principal investigator on the NSF grant.
Co-principal investigators on the project are physics professor Sol
Gruner and professors of mechanical and aerospace engineering Lance
Collins and Zellman Warhaft.
Turbulent fluid flows are among the most mathematically complex
phenomena in nature. Capricious and chaotic, they present a
formidable challenge to the researcher seeking to form abstract
theory from empirical observation. "At a small enough scale, all
turbulence behaves the same way," says Bodenschatz. "Whether I do an
experiment and study turbulence, or whether I take a car engine and
there's some exploding gasoline in there, the mixing properties
should be the same."
The problem is an extremely complicated one, says Bodenschatz. "Say
you want to predict where the next swirl will be -- you cannot say
that. They're unpredictable. They're the most chaotic thing you can
imagine. That's why when an airplane approaches possible air
turbulence, pilots will say, 'most likely we will get turbulence.'
They don't know when it will happen."
One challenge in turbulence research lies in tracking the erratic
paths of the particles as they dip and swirl. Currently available
technology, like the silicon strip detectors used in Bodenschatz's
laboratory, captures only a few particles at a time.
With the NSF grant, the Cornell scientists will construct an array of
four digital cameras that will take pictures of the tiny, flying
polystyrene spheres in three dimensions. The device will capture up
to 100,000 frames per second -- compared with 30 frames per second
for an ordinary video camera. A 64-processor computer cluster will
then analyze the photos and construct three-dimensional flight
trajectories for each individual particle.
The instrument will allow researchers to follow not just a few, but
many hundreds of particles, in flows with Reynolds numbers (a measure
of the intensity of the turbulence) hundreds of times higher than
those previously observable.
This release was prepared by Lissa Harris, a Cornell graduate student
and Cornell News Service science-writing intern.
Related World Wide Web sites: The following site provides
additional information on this news release
o Complex Matter Physics Group: <http://milou.msc.cornell.edu/>
-30-
The web version of this release may be found at
http://www.news.cornell.edu/releases/March03/Bodenschatz.award.lh.deb.html
Cornell University News Service
Surge 3
Cornell University
Ithaca, NY 14853
607-255-4206
cunews_at_cornell.edu
http://www.news.cornell.edu
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