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Anonymous Poster

a little fluid dynamics

07/18/2009 2:35 PM

Hello, I have a question about fluidmechanics, this is probably very easy and basic, but I just cant understand it.

Lets say that we have a sylinder in a moving flyid, and the fluid motion is directed normal to the cylinders axis.

My book says that then the preassure of the fluid in front of the cylinder first decreases along the surface and then it increases(causeing a wake). But my book does NOT explain why we have this preassure difference, can anyone please explain this to me.
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phoenix911
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#1

Re: a little fluid dynamics

07/18/2009 3:48 PM

Guest,

Nothing can be simple in fluid dynamics, but,.......

What is happening is called principal of conservation of energy and to drill it down even farther is whats called Bernoulli's principle

This should help explain it without me having to reiterating it.

http://en.wikipedia.org/wiki/Bernoulli%27s_equation

hope this helps,

phoenix911

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phoenix911
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#2
In reply to #1

Re: a little fluid dynamics

07/18/2009 4:29 PM

One more thing, what can also happen is a thing called Vorticity Shedding.

check wiki

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Anonymous Poster
#3

Re: a little fluid dynamics

07/18/2009 4:40 PM

Are you refering to the explanation that since we get velocity changes then the preassure changes?
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TVP45
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#4

Re: a little fluid dynamics

07/18/2009 7:16 PM

This is inviscid, but that's always a good starting point.

http://www.av8n.com/irro/cilindro_e.html

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