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-   -   Cell centroid and cell volume in general, and in Fluent (https://www.cfd-online.com/Forums/main/69158-cell-centroid-cell-volume-general-fluent.html)

 zmester October 13, 2009 18:07

Cell centroid and cell volume in general, and in Fluent

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.

 esozer October 17, 2009 10:09

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.

 zmester October 17, 2009 10:55

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.

 esozer October 17, 2009 11:05

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.