# [blockMesh] Cyclic BC's: Possible face ordering problem? (Channel flow)

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May 5, 2009, 16:22
Cyclic BC's: Possible face ordering problem? (Channel flow)
#1
Senior Member

Sebastian Gatzka
Join Date: Mar 2009
Location: Frankfurt, Germany
Posts: 729
Rep Power: 20
Hello World.

I'm doing a rather complex mesh for channel flow using 36 blocks to get the appropriate mesh resultion at the walls.

The mesh despriction itself is working brilliant, but when I try to set the cyclic boundary conditions I'm getting this error:

Code:
face 1 area does not match neighbour 36 by 160% -- possible face ordering problem.
patch:INOUT my area:36 neighbour area:4 matching tolerance:0.001
Mesh face:61 vertices:4((0 2 0) (0 20 0) (0 20 2) (0 2 2))
Neighbour face:96 vertices:4((300 0 2) (300 2 2) (300 2 0) (300 0 0))

From function cyclicPolyPatch::calcTransforms()
in file meshes/polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C at line 150
Can you tell me what I should look at in my blockMeshDict concerning this error?
I'm not sure what is meant by the "possible face ordering problem".
Attached Files
 blockMeshDict.tar.gz (2.1 KB, 53 views)
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 May 6, 2009, 09:32 #2 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 20 Well, I simply forgot one patch (containing four vertices). That solved the problem. Another question: Do the patches of in- and outflow have to be exactly opposite of each other? That would mean after the list of inflow-patches is finished, I have to start with the patch opposite of the very first one? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 September 28, 2010, 12:46 #4 Senior Member     Join Date: Jan 2010 Posts: 347 Blog Entries: 2 Rep Power: 17 i need help too about this problem