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| Experiment
Description |
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Rayleigh-Taylor
instability is a very fundamental fluid instability that
occurs whenever a heavier fluid is placed on top of a
lighter fluid in a constant gravitational field. It is
of importance to a wide variety of applications ranging
from oceanography to inertial confinement fusion. The
instability can most easily be demonstrated by simply
inverting a stably-stratified system (by for example
turning over a glass of water). However, the disruptive
effects produced by the inversion process make this
method unsuitable for studying the instability in a
controlled laboratory environment.
Rayleigh-Taylor instability is generated in our
experiments by accelerating a tank containing the two
fluids downward at a rate greater than the earth's
gravitational acceleration. The experimental apparatus
consists of a tank that is mounted to a linear rail
system and attached by a cable to a
weight and pulley system. The bottom half of the
tank is filled with a heavy liquid and the top half with
a lighter liquid. The filled container is then hoisted
to the top of the rail system and then oscillated in the
horizontal direction giving the interface a sinusoidal
initial perturbation. The tank is then released allowing
the weight to pull it downward at a rate approximately
twice that of the earth's gravitational field which
produces a net gravitational pull approximately equal to
that of the earth's but oriented upward. Thus, the
initially stably-stratified system becomes unstable.
The fluids are visualized in these experiments using
Planar Laser Induced Fluorescence. A fluorescent dye is
mixed in one of the liquids and then illuminated with a
sheet of laser light passing through the top of the
container. The resulting fluorescent images are captured
by a CCD camera which travels with the moving container.
Pictures below shows a sequence of images captured
during one of these experiments. In these views the
effective gravity pulls the lower heavier fluid upward
as if the tank had been inverted but without the
disrupted effects of actually turning over the tank. |
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| Experiment
animation |
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File size: 276.09
KBytes
Estimated download time: 107.98 sec at 28.8 Kbps 54.94
sec at 56.6 Kbps
256 Color Palette |
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Page last updated:
08.17.2005 |
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