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pipe flow with noozle - ? on BC's

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Old   March 14, 2011, 06:08
Default pipe flow with noozle - ? on BC's
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mediode
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Hello Forum!

Maybe simple, but I am not sure about the following ....

I am currently dealing with the attached geometry, a pipe system with known velocity at the inlet. The pipe finally end in an reservois with a liquid with known level, which corresponds to a known static pressure if I only consider the pipe (not the reservoir) in my calculations. At the top, geometrically above the reservoir, the pipe has a noozle where the liquid can drop out. I want to know the quantity of liquid that leaves the pipe through the nozzle.

My prob: Which pressure-BC has to be choosen at the noozle? Simply p=0 or have I to refer to the static pressure at the end of the pipe and consequently to the bath level in the reservoir?

Your comments are appreciated!

m*
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Old   March 14, 2011, 06:57
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Raashid Baig
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Quote:
Originally Posted by mediode View Post
Hello Forum!

Maybe simple, but I am not sure about the following ....

I am currently dealing with the attached geometry, a pipe system with known velocity at the inlet. The pipe finally end in an reservois with a liquid with known level, which corresponds to a known static pressure if I only consider the pipe (not the reservoir) in my calculations. At the top, geometrically above the reservoir, the pipe has a noozle where the liquid can drop out. I want to know the quantity of liquid that leaves the pipe through the nozzle.

My prob: Which pressure-BC has to be choosen at the noozle? Simply p=0 or have I to refer to the static pressure at the end of the pipe and consequently to the bath level in the reservoir?

Your comments are appreciated!

m*
Hi,
I think the pressure at the nozzle exit should be atmospheric pressure (Adjusted according to the reference pressure that you have taken for your working fluid) and it has nothing to do what pressures you have specified at the pipe ends.
Raashid
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Old   March 14, 2011, 11:31
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mediode
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Thank you for your suggestion!

At present I think it is of of major importance if gravity is regarded or not. I'm intending to use a solver that doesn't.

If NO velocity-BC would be applied, flow would develop from the reservoir to the nozzle in a case with p=rho*g*h at the reservoir and p=0 at the nozzle. As a consequence p=0 at the outlet AND the nozzle would be the right pressure BC, or?

m*
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