[aqua]

Originally Posted by fs82

Yeah I found the problem. For everyone who is dealing with the same problem concerning cyclic boundaries in OpenFoam try the following:

1) as mentioned above from chegdan, make sure that you have linked all your faces correctly (Reverse orientation switch in Gambit have to be ON)

2) if you have split your perodic boundaries into parts to help gambit for meshing, put every part of your periodic boundary into one patch. Do not put both faces which should be periodic into the same boundary patch. They have to be separate patches.

3) export mesh with Gambit

4) use fluentMeshToFoam

5) create a CreatePatchDict dictionary in system/ folder and combine your separate perodic patches to one. For type use cyclic. Do not touch constant/polymesh/boundary for this step.

Example:
{
name pz_1;
type cyclic;
constructFrom patches;
patches (pz_1 pz_1shadow);
set f0;
}

6) run createPatch utility. This will combine the periodic patches to one and renumber it for OpenFoam.

7) open constant/polymesh/boundary and change wall to cyclic for your periodic boundaries. Do not forget to change your createPatchDict, because you have combined two patches to one right before.

8) rerun createPatch for making your boundaries perodic

This should work und looks good for me. I guess the problem ist Gambit, which numbers the faces without any order if you put both parts of your perodic boundary into one patch. I think fluent does not care about the numbering of the boundary faces but OpenFoam (CreatePatch) does. So for me it works :-D

Thx chegdan for your help.

Fabian

Edit: If you still have Problems: Make sure you have set WritePrecision in controlDict to a value greater than 10. Also try to remove functions from controlDict (comment them out).

Dear Fabian,
I created my mesh by blockMesh, snappyHexmesh, but still have the problem
"face 391 area does not match neighbour 791 by 0.0136179% -- possible face ordering problem."
I also set writeprecision as 10..
Could you please give some suggestion? Thank you so much!
Aqua

[vishalsacharya]

Dear aqua,

In "createPatchDict" file from the applications/utilities/mesh/manipulation folder, you will see the following...

// 2. Correct incorrect cyclic:
// This will usually fail upon loading:
// "face 0 area does not match neighbour 2 by 0.0100005%"
// " -- possible face ordering problem."
// - in polyMesh/boundary file:
// - loosen matchTolerance of all cyclics to get case to load
// - or change patch type from 'cyclic' to 'patch'
// and regenerate cyclic as above

So, you can loosen matchTolerance of your cyclics to get it to work or change the patch type to patch from cyclic and use createPatch to make your cyclic. Hope this helps, let me know.

[aqua]

Originally Posted by vishalsacharya

Dear aqua,

In "createPatchDict" file from the applications/utilities/mesh/manipulation folder, you will see the following...

// 2. Correct incorrect cyclic:
// This will usually fail upon loading:
// "face 0 area does not match neighbour 2 by 0.0100005%"
// " -- possible face ordering problem."
// - in polyMesh/boundary file:
// - loosen matchTolerance of all cyclics to get case to load
// - or change patch type from 'cyclic' to 'patch'
// and regenerate cyclic as above

So, you can loosen matchTolerance of your cyclics to get it to work or change the patch type to patch from cyclic and use createPatch to make your cyclic. Hope this helps, let me know.

Dear vishalsacharya,
Thank you so much for your kind reply. I knew the matchTolerance, so I tried to give it a big value, even 3. but it still didn't work.
For me the interesting thing was:
I could create the cyclic in OF2.0 with a matchTolerance of 0.001;
But I couldn't create the cyclic in OF 1.6-ext even the matchTolerance was 3...

So I assumed that OF1.6ext has something not that right...

cheers!

Aqua