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-   -   Calculating average pressure (http://www.cfd-online.com/Forums/paraview/105894-calculating-average-pressure.html)

julien.decharentenay August 12, 2012 06:35

Calculating average pressure
 
Hi,

I am trying to validate openFoam simulation against experimental results for the Turbine 99 case (see https://dl.dropbox.com/u/40499338/tu...9-geometry.jpg for picture of the geometry, see http://pure.ltu.se/portal/en/publica...a68e967b).html for copy of the documentation describing the case).

One of the parameters that is to be extracted is the averaged pressure along the wall at the inlet (see the white circle on https://dl.dropbox.com/u/40499338/tu...99-pinwall.jpg) - pressure recovery factor described in page 16 of the proceeding (link above). I have done the following:

1) Load the openFoam case with showing only the walls;
2) Create a slice of the wall (which creates the white circle);
3) Apply the "Integrate Variables" filter on the slice;

My assumption is that the average pressure could be obtained by selecting "Cell Data" under the Attribute drop down menu and dividing the pressure by the length. Is this approach correct?

Based on the above approach, the mean pressure is approx -5 (~-12/2.5), which is too low and seems not consistent with the color plots that seems to indicate that the pressure is between -7 and -10.

Thanks a lot if you can help me in either finding another method or clarifying where I am going wrong.

Kind regards,
Julien

nash August 19, 2013 07:50

i think what you got from the integrate variable for p is not the average pressure visualized in paraview, but it is the integration of pressure over surface which is also the force acting on the surface.

since the definition of p=F/A


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