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Science Forum Index » Physics - Research Forum » Bernoulli effect for spinning disks...
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| cyber one... |
 Posted: Mon May 05, 2008 4:40 pm |
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Guest
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For a stationary disk, the air pressure on the platter is atmospheric
pressure.
For a disk spinning at 10,000 RPM, say 140 miles per hour for a 5.25
inch disk, I assume the Bernoulli effect would reduce the pressure,
but because of the Ekman flow, the pressure would be more than the
pressure would be on a non-rotating disk in which the air was moving
over the disk surface linearly at 120 miles per hour.
The so-called no-slip property of gas-solid interfaces requires that
the gas in the immediate vicinity of a spinning disk move with the
disk. Unlike the solid comprising the disk, however, the gas spinning
with the disk cannot withstand the concomitant centrifugal force. The
resulting outward spiraling flow is called Ekman flow.
Can you give me an approximate estimate of the percentage of
atmospheric pressure a spinning disk platter at 10,000 RPM would
"experience"? |
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