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Topic Name: Complex tangle of curves corresponding to two very different motions of particles in the flow.
Category: Mechanical
Research persons: Graduate student Manikandan Mathur. Mathur,Dr. George Haller,Dr. Thomas Peacock
Location: 1 University Station C1600,Austin, Tx 78712-0264,University of Texas at Austin, United States
Details
The convoluted
tangle describing turbulence has been visualized for the first time by a group
of researchers from The University of Texas at Austin and the Massachusetts
Institute of Technology (MIT).
Their work, published in the April 6 issue of Physical Review Letters, may
ultimately help engineers design more efficient planes, cars, submarines and
engines.
Turbulence is important in almost all phenomena involving fluid flow, such as
air and gas mixing in an engine and air whipping across the surface of a
vehicle. However, a comprehensive description of turbulent fluid motion remains
one of the major unsolved problems in physics.
The research
revealed an underlying skeleton of turbulence, which is a complex tangle of
curves corresponding to two very different motions of particles in the flow.
The first type
of curve attracts fluid particles, while the second type of curve repels fluid
particles. These two sets of curves repeatedly cross one another, forming a
dense evolving tangle that is the skeleton of turbulence.
Laboratory
experiments were designed and conducted by doctoral student Jori Ruppert-Felsot
and his adviser, Physics Professor Harry Swinney, in The University of Texas at
Austin's Center for Nonlinear Dynamics.
They produced
turbulence by rapidly pumping water into and out of a rotating two-foot high
cylindrical tank. The influence of the rotation was comparable to the effect of
the Earth's rotation on atmospheric and oceanic turbulence.
"The experiment
was designed to achieve a better understanding of the kind of turbulence that
occurs in the atmosphere and oceans, where the Earth's rotation strongly affects
the flow and leads to structures such as hurricanes and atmospheric high- and
low- pressure systems," said Swinney.
The researchers
determined the speed of the flows by using laser imaging techniques to track
tiny particles seeded in the fluid.
The technical
analysis of the flow velocity was carried out by MIT mechanical engineering
graduate student Manikandan Mathur. Mathur's work is jointly supervised by MIT
co-authors Dr. George Haller, professor of mechanical engineering, and Dr.
Thomas Peacock, assistant professor of mechanical engineering.
Using
mathematical tools, Mathur uncovered a convoluted tangle embedded in the flow.
MIT's
image of the turbulent flow is available online. In the image, the
attracting curves are colored red and the repelling curves are colored blue.
This research
was supported by the Office of Naval Research, the National Science Foundation
and the Air Force Office for Scientific Research.
A
high-resolution image of the chaotic tangle underlying turbulence is available
by contacting Lee Clippard,
512-232-0675
About
researchers:
Harry L. Swinney
Sid Richardson
Foundation Regents Chair, Department of Physics
swinney@chaos.ph.utexas.edu
(512)-471-4619
Office: RLM 14.224
George Haller
Professor of
Mechanical Engineering
Room 3-352
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge MA 02139-4307
Phone: 617-452-3064
Fax: 617-258-6771
Email: ghaller@mit.edu
Web:
http://www.mitnonlinear.com/
Thomas Peacock
Atlantic
Richfield Career Development Assistant Professor of Mechanical Engineering
Room 1-310D
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge MA 02139-4307
Phone: 617-258-0736
Fax: 617-258-8744
Email: tomp@mit.edu
Web:
http://web.mit.edu/peacocklab
Funded:
This research
was supported by the Office of
Naval Research, the National Science
Foundation and the
Air Force Office for Scientific Research
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