[make]

Hi,

I have an rotational symmetric grid which I use within CFX. Therefore it has two patches called SYM_1 and SYM_2 linked within CFX as fluid-fluid interface.

I use icem to create the grid and then save it as fluent_v6 mesh. Everytime I try to match these to patches to one cyclic patch using the createPatch tool I get the following errror message.

Removing empty patch SYM_1
Removing empty patch SYM_2
Compacted patches:
WALL size:3036 start:281298
INLETP size:44 start:284334
INLETS size:44 start:284378
INLETB size:12 start:284422
OUT50 size:60 start:284434
OUT70 size:28 start:284494
OUT100 size:44 start:284522
SYM size:0 start:284566
--> FOAM Serious Error :
From function cyclicPolyPatch::order(const primitivePatch&, labelList&, labelList&) const
in file meshes/polyMesh/polyPatches/derivedPolyPatches/cyclicPolyPatch/cyclicPolyPatch.C at line 702
patch:SYM : Cannot match vectors to faces on both sides of patch
half0Ctrs[0]-0.0366477 0.00571359 -0.000299436)
half1Ctrs[0]-0.0366477 0.00571359 -0.000299436)
Please use topological matching or adapt the featureCos() setting
Continuing with incorrect face ordering from now on!
Writing repatched mesh to 1
End

I read all treads I found in the forum dealing with the same error message as above, but there is one difference here. My patches are absolutely planar and the center coordinates in the error message are identical. I also renumered the nodes in CFX and run all error checks. The mesh seems to be fine. It is also not the first grid of this kind which I build in that way. So far all of them worked well. Has anybody experienced anything similar?

[hjasak]

In OpenFOAM, both sides of a cyclic need to be in a single patch, properly ordered. Are yours done like that?

Hrv

[make]

That's what I did with createPatch:
{
name SYM;
type cyclic;
constructFrom patches;
patches (SYM_1 SYM_2);
}
);
I have them in two patches cause CFX needs them to be in two patches.
I also exported my mesh having both sides in one patch and then used couplePatches to order them correctly, same error. I used that geometry before and it worked. Then I changed the blocks to have an OGrid on the axis to improve quality. First I made a coarse grid and this one worked. Now I refined it and since then I have this troubles.

[mattijs]

couplePatches takes all the faces in a cyclic patch, tries and divide it into two separated halves (either topologically split or split by a feature edge), works out a transformation tensor/displacement vector from two faces, one on either side (note that this will go wrong for non-planar halves) and determines a correspondence between the faces.

Switch on the debug switches for coupledPolyPatch and cyclicPolyPatch and have a look through the code.

[make]

Hi Hrvoje and Mattijs,

thank you both for your assistance. I browsed through the code and saw that definition and structure of my grid is OK. So I guessed that the failure must lie in the accuracy of my grid points. Having a look in my fluent.msh file showed small differences in the position of the twin vertices.So, I checked the twin nodes in ICEM. During the refinement of the mesh some few twins have been lost. I redefined them and everything is fine now.
That was really like looking for a needle in a haystack.
Thank you again for your help!

[mattijs]

createPatches will create a new patch if it does not exist yet. If it already exists it does not change the type.

[mahendra]

Dear Mattijs,

Thanks for the quick reply.

So how should I make patches those are cyclic on a mesh I imported form Gambit/Fluent?

Regards,
Mahendra.

[mahendra]

Any reply for making cyclic boundaries on a mesh imported form Gambit/Fluent???

Regards,
Mahendra