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Cell centroid and cell volume in general, and in Fluent

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Old   October 13, 2009, 19:07
Default Cell centroid and cell volume in general, and in Fluent
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Zoltán Hercz
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Hi

Is there anyone who can explain me how do the cell centroid(c_centroid) and cell volume(C_Volume) functions of Fluent work? What method they use to calculate the centroid and the volume of a cell. Im writing my code, and would like to create functions similar to these.Thanks.
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Old   October 17, 2009, 11:09
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Emre
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I don't how fluent does this but the following will work for arbitrary cell geometries:

Code:
Loop faces
   Loop face nodes
     Form a triangle using two subsequent face nodes and a point within the face (e.g  average of face nodes)
     Calculate the resulting triangle area
     Add to face area
     Form a tetra using the triangle and a point within the cell volume
     Calculate tetra volume
     Add to cell volume
     Tetra centroid is known (google it)
     cell_centroid=cell_centroid+tetra_volume*tetra_centroid
   End face node loop
End face loop

cell_centroid=cell_centroid/cell_volume
Hope this helps.
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Old   October 17, 2009, 11:55
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Zoltán Hercz
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Thank you for your answer. Since i asked i have already find an other method using the divergence theorem (Gauss) to transform volume integrals to surface integrals.
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Old   October 17, 2009, 12:05
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Right, that will work too. I preferred the method I described since it will give the face areas, face centroids, cell volumes and cell centroids in one swipe.

Good luck with your code.
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