CyclicAMI: Match Tolerance

Alasir · October 17, 2017, 18:40

Hi

Im wondering how the Matchtolerance value used in the cyclicAMI BC is generally used.

Is it the tolerance relative to the size of the mesh? Or would a mesh in micrometer need orders of magnitude lower tolerance than a mesh in millimeters?

What are typical values?

What are the common sideeffects of putting the value to high or to low?

Any answers to any of these questions would be appreciated.

keitaro7_14 · May 13, 2019, 10:42

I'm not 100% sure, but matchTolerance makes sense in a cyclic path, when the two faces have to match.

In cyclicAMI and cyclicACMI patches, it is included to match the cyclic template, but its value is not relevant.

It is my opinion, I'm not sure. Citing the documentation:

cyclic: enables two patches to be treated as if they are physically connected; used for repeated geometries; one cyclic patch is linked to another through a neighbourPatch keyword in the boundary file; each pair of connecting faces must have similar area to within a tolerance given by the matchTolerance keyword in the boundary file.
cyclicAMI: like cyclic, but for 2 patches whose faces are non matching; used for sliding interface in rotating geometry cases.

AmrShaalan · April 29, 2024, 12:12

I realize this question was asked a long time ago but for anyone who had that question, this is what match tolerance means:

From https://doc.cfd.direct/openfoam/user...-v8/boundaries
"one cyclic patch is linked to another through a neighbourPatch keyword in the boundary file; each pair of connecting faces must have similar area to within a tolerance given by the matchTolerance keyword in the boundary file."

So it is essentially the ratio between the cells on both patches to be considered a "match"

October 17, 2017, 18:40	CyclicAMI: Match Tolerance	#1
Alasir Member Anders Utnes Join Date: May 2017 Location: Norway Posts: 34 Rep Power: 9	Hi Im wondering how the Matchtolerance value used in the cyclicAMI BC is generally used. Is it the tolerance relative to the size of the mesh? Or would a mesh in micrometer need orders of magnitude lower tolerance than a mesh in millimeters? What are typical values? What are the common sideeffects of putting the value to high or to low? Any answers to any of these questions would be appreciated.

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May 13, 2019, 10:42		#2
keitaro7_14 Member JuanMi Join Date: Nov 2017 Posts: 41 Rep Power: 9	I'm not 100% sure, but matchTolerance makes sense in a cyclic path, when the two faces have to match. In cyclicAMI and cyclicACMI patches, it is included to match the cyclic template, but its value is not relevant. It is my opinion, I'm not sure. Citing the documentation: cyclic: enables two patches to be treated as if they are physically connected; used for repeated geometries; one cyclic patch is linked to another through a neighbourPatch keyword in the boundary file; each pair of connecting faces must have similar area to within a tolerance given by the matchTolerance keyword in the boundary file. cyclicAMI: like cyclic, but for 2 patches whose faces are non matching; used for sliding interface in rotating geometry cases.

April 29, 2024, 12:12		#3
AmrShaalan New Member Amr Shaalan Join Date: Sep 2017 Posts: 4 Rep Power: 9	I realize this question was asked a long time ago but for anyone who had that question, this is what match tolerance means: From https://doc.cfd.direct/openfoam/user...-v8/boundaries "one cyclic patch is linked to another through a neighbourPatch keyword in the boundary file; each pair of connecting faces must have similar area to within a tolerance given by the matchTolerance keyword in the boundary file." So it is essentially the ratio between the cells on both patches to be considered a "match"