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Importing 3D mesh from ANSYS to OpenFOAM

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Old   September 3, 2012, 19:12
Question Importing 3D mesh from ANSYS to OpenFOAM
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Hugh Ingham
Join Date: Aug 2012
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Hi all,
I have created a 3D mesh to be used for a LES simulation using ANSYS meshing, however I am having problems with the cyclic boundary conditions when I import it into OpenFOAM.

When making the mesh I basically swept a 2d mesh through a wedge and used face matching so that the face on each side of the wedge is exactly the same. I also set up a 'cyclic region' using the 2 faces and then exported it.

Upon importing it into FOAM using fluent3DToFoam it passes all the mesh checks and I can view it in paraFoam. However, it imports it with the 2 boundaries as type: symmetryPlane. When I change the boundary file to type: cyclic, and define the other relevant information, it says:

--> FOAM FATAL ERROR:
face 0 area does not match neighbour by 140.577496188% -- possible face ordering problem.
patch:symmetry1 my area:1.2669562804e-06 neighbour area:7.26150481844e-06 matching tolerance:0.0001
Mesh face:539866 fc0.089354599 0.032148637105 0.032148637105)
Neighbour fc0.6325670359 0.042837176385 0)
If you are certain your matching is correct you can increase the 'matchTolerance' setting in the patch dictionary in the boundary file.
Rerun with cyclic debug flag set for more information.

From function cyclicPolyPatch::calcTransforms()
in file meshes/polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C at line 220.

FOAM exiting


Here are some images of the mesh:

meshpic.jpg

meshpic2.JPG



Here is the boundary file:



// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

6
(
wall-part-solid
{
type wall;
nFaces 66;
startFace 538534;
}
inlet
{
type patch;
nFaces 266;
startFace 538600;
}
nozzlewall
{
type wall;
nFaces 1000;
startFace 538866;
}
symmetry1
{
type cyclic;//symmetryPlane
nFaces 18500;
startFace 539866;
matchTolerance 0.0001; // not required for sym
neighbourPatch symmetry2; // not required or sym
}
freestream
{
type wall;
nFaces 3600;
startFace 558366;
}
symmetry2
{
type cyclic;//symmetryPlane
nFaces 18500;
startFace 561966;
matchTolerance 0.0001; // not required for sym
neighbourPatch symmetry1; // not required for sym
}


How is this mismatch possible when in the boundary file each patch has the same nFaces and the mesh is the same on both sides? What does it mean by possible face ordering problem? I was told that if the cyclic region is defined in your mesher then everything would be in the right order.
Also, I imported the mesh without defining the cyclic region in ANSYS and it came up with the same error but with a figure of about 176%.

How do I fix this? Any help would be appreciated.

Thanks, Hugh
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ansys mesher, cyclic bc, mesh conversion, open foam

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