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March 14, 2012, 00:33 |
Force on a patch
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#1 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
I need to calculate the force caused by the flow on a patch.
In the first picture you can see the result of the simpleFoam solver. In the second there's the patch I want to calculate Fx on. I tried in Parafoam to integrate pressure on the surface but maybe I miss something (BTW, is there a tutorial regarding this managements ?) Another simple question: p for incompressible solver is actually divided by density. That means that the real pressure at the end has to be multiplied by density, right ? Daniele |
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March 14, 2012, 03:04 |
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#2 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Probably I should have posted this under the parafoam forum. Is there any way to move it by me ?
Anyway, I tried the following in Parafoam: 1. Select the above patch. 2. Generate surface normals. 3. Use calculator to define a new var called Px defined as p*N_x*1000. (where 1000 is density of water). 4. Integrate Px on the surface. Is it correct ? The obtained value is in Newton, right ? |
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March 15, 2012, 01:42 |
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#3 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Another way, more flexible is to use the libforces library as follow:
Code:
functions { forcespisto { type forces; functionObjectLibs ("libforces.so"); //Lib to load patches (pisto); // change to your patch name pName p; Uname U; rhoName rhoInf; rhoInf 1000; CofR (0 0 0); //Origin for moment calculations outputControl timeStep; outputInterval 5; } } Just a confirmation: is it right ? Daniele |
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March 15, 2012, 04:54 |
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#4 |
Senior Member
Aurelien Thinat
Join Date: Jul 2010
Posts: 165
Rep Power: 15 |
Hi Daniele,
Yes it is. Just modify the CoR (center of reference) if you want the values of Mx My and Mz. There is also a "forceCoeffs" function for Cx Cy and Cz calculations. Aurélien |
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