# unstructured grid wall cells algorithm

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 September 9, 2015, 04:42 unstructured grid wall cells algorithm #1 Member   Shah Join Date: Aug 2013 Posts: 61 Rep Power: 10 How do we find whether a cell is located at the wall. How would the algorithm do it ? Thanks in advance shah

September 9, 2015, 09:53
#2
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Michael Prinkey
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Location: Pittsburgh PA
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Quote:
 Originally Posted by researcher How do we find whether a cell is located at the wall. How would the algorithm do it ? Thanks in advance shah
If you are talking about an unstructured code like FLUENT or OpenFOAM, to touch all of the cells adjointing a wall boundary, you loop over the faces in the wall thread/patch and look up the cell connected to each face (F_C0() in FLUENT, etc).

 September 10, 2015, 07:09 #3 Member   Shah Join Date: Aug 2013 Posts: 61 Rep Power: 10 Thank you for your reply. In fact I am programing it using fortran. Plus I am using unstructured mesh. I am curious how would a triangular cell with only one of its vertices located on the wall effect the algorithm. Thanks

September 10, 2015, 08:00
#4
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Michael Prinkey
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Quote:
 Originally Posted by researcher How do we find whether a cell is located at the wall. How would the algorithm do it ? Thanks in advance shah
Quote:
 Originally Posted by researcher Thank you for your reply. In fact I am programing it using fortran. Plus I am using unstructured mesh. I am curious how would a triangular cell with only one of its vertices located on the wall effect the algorithm. Thanks
It won't. If you are using FVM, the entire scheme is based on surface integrals over each cell. A single vertex has no area to integrate over, so its contribution is zero. Only finite area faces will contribute to the flux balances that you write for each cell.

September 10, 2015, 10:06
#5
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Shah
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Quote:
 Originally Posted by mprinkey It won't. If you are using FVM, the entire scheme is based on surface integrals over each cell. A single vertex has no area to integrate over, so its contribution is zero. Only finite area faces will contribute to the flux balances that you write for each cell.

 Tags unstructured grid, wall cells algorithm