[PeterShi]

Hello everyone,

I met a weird problem: the far field of my mesh is a cylinder, and I set two base faces of this cylinder as "cyclic". Let's call them "front" and "back". When I generated mesh, I simply translated "back" to get "front" using vector (0 0 0.005) shown as below.

back
{
type cyclic;
inGroups 1(cyclic);
nFaces 39660;
startFace 2536318;
matchTolerance 1000;
transform translational;
neighbourPatch front;
separationVector (0 0 0.005);
}

front
{
type cyclic;
inGroups 1(cyclic);
nFaces 39660;
startFace 2576138;
matchTolerance 1000;
transform translational;
neighbourPatch back;
separationVector (0 0 -0.005);
}

After obtaining the mesh I generated, I used command "renumberMesh", and it reports the following message:

---------------------------------------------------------------------------------
--> FOAM Warning :
From function void Foam::cyclicPolyPatch::calcTransforms(const primitivePatch&, const pointField&, const vectorField&, const pointField&, const vectorField&)
in file meshes/polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C at line 360
Specified separationVector (0 0 0.005) differs from computed separation vector

39660
(
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 1.0842e-19 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 -4.33681e-19 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(1.11022e-16 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 2.1684e-19 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 8.67362e-19 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 0 0.005)
(0 -6.93889e-18 0.005)
...
... (a lot of vectors like that)

This probably means your geometry is not consistent with the specified separation and might lead to problems.
Continuing with specified separation vector (0 0 0.005)
patch:front neighbour:back
---------------------------------------------------------------------------------

I have no idea about what is wrong, I mean I am pretty sure I translated the face using (0 0 0.005), why it says your geometry is inconsistent with the separation vector. As a result, I did run this mesh, but it diverges very soon after 13 iterations. My mesh is not bad, so I believe the divergence is coming from this problem.

I also have another question: any user has tried "cyclic" and "cyclicAMI" for the same case? If so, have you observed differences in your results? Is cyclicAMI reliable?

Any advice, comment, and discussion here is highly appreciated. Thank you.

Best regards,
Peter