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-   -   Zero area faces on the axis as symmetryPlane (http://www.cfd-online.com/Forums/openfoam-solving/59379-zero-area-faces-axis-symmetryplane.html)

make October 16, 2007 04:03

Dear All, I'm calculating a
 
Dear All,

I'm calculating a combustion chamber. The combustion chamber is a 1 cell thick rotational symmetric grid (cyclic not wedge type).
In CFX I use a symmetry bc for the axis. The axis consists of zero area faces only
I tried to use this grid also in OpenFOAM. I could transform it into an openFOAM grid by using the fluent3DToFoam tool after removing the periodic shadow faces. I've then taking into account the periodicity, applying couplePatches. So far everything went fine.
I defined the zero area elements on the axis as symmetryPlane as I did in CFX. Starting a calculation leads now to a floating point exception ( most likely division by zero).
Running checkMesh leads to some complains about 0 area faces (not surprisingly) and also some missoriented elements. The check for missoriented elements in ICEM doesn't show any.

My questions is now:
- Is it in general possible to use zero area
faces as symmetry in OF or do I have to retain
small area faces on the axis.
- Can I fix missoriented elements in OF.

hjasak October 16, 2007 05:12

Yes, division by zero: either
 
Yes, division by zero: either collapse the faces or make them "small" + put a symmetry plane boundary condition on them.

Enjoy,

Hrv

make October 16, 2007 05:47

That did it! I made them real
 
That did it!
I made them really small and put a symmetry plane on them, works fine.

Thanks really a lot,
Matthias


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