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-   -   How to get the output pressure of OpenFoam? (https://www.cfd-online.com/Forums/openfoam-post-processing/180538-how-get-output-pressure-openfoam.html)

IGH November 25, 2016 04:56

How to get the output pressure of OpenFoam?
 
Hi,

I am new to OpenFoam, so sorry if this is a basic question.
I am using OpenFoam for solving the forces and moments on a 2D rectangulat tank with motion. but first I am doing some simulation on a static tank at rest (without any motions) so that we know all the pressure at tank bottom theoretically and we can check to see if we are using the OpenFoam at right setup.
when I use the pressure probes at bottom of the tank, I get some values that I don't understand them at all. what do we get (at which dimension) as output when we want P out of the probes?
I get some values like +11 as p-rgh and values like -0.4 as P.
the tank depth is 4cm and tanktop is open atmosphere.

Thanks

saeed.barzegar.v October 4, 2017 09:36

Hi Isar, How are you?

I had same problem recently and I think you got those values because your probes' locations were out of your computational domain.

IGH October 4, 2017 09:56

Hi Saeed. Thanks.
No that was not my problem. Normally it gives the pressures relative to a basic pressure at a predefined point. So one should define that point in air domain normally to get some meaningful pressure values at other probes, otherwise it seems nonsense.

saeed.barzegar.v October 4, 2017 10:38

Yes, you are right. That is reference pressure and it must be assigned to a specific cell. And it is suggested to define this cell in the air phase for two-phase flow problems.


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