## A question about fluid dynamics

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terje
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### A question about fluid dynamics

Hi every one.

Iâ€™m trying to understand the basics of fluid dynamics, and hope there is some here one who can help me explain this.

So letâ€™s see if I understood this correctly.
An air stream blowing across a surface would cause a lower pressure on the surface then as if the air where at rest. If the surface where perforated with small holes, and the air under the surface where still. Then the air stream would pull air trough the holes due to the venturi-effect. Now, if the perforated surface where the top of an air tight box, this would cause an under-pressure in the box. Is this correct?

So this is my question: How do I calculate these pressures, with different airspeeds? Say, 1m/s 5m/s and 15m/s.
I assume there is 4 different pressures to take in to account.
P1: air at rest, this could be normal atmospheric pressure at sea level.
P2: pressure on a cross section, perpendicular to the stream. Guess this would be the ram pressure.
P3: pressure on a point drifting with the stream.
P4: pressure in the box.
:)
/Terje
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mk
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Would not (hydro-)dynamic pressure or Bernoulli or gas pressure represent suitable keywords for a first search?

mk

leo
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### bernoulli search

If you do a search watch out for incorrect explanations see the following links.

airfoil

nasa

nasa

terje
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Thanks.
I also found this site with, in my opinion, good and basic explanations of physics.
http://hyperphysics.phy-astr.gsu.edu/hbase/bercon.html
Iâ€™m still struggling to grasp the concepts, but Iâ€™ll get trough it.The math is not my strongest side. :)