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Old   April 20, 2005, 23:37
Default You can make sure by setting s
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Mattijs Janssens
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You can make sure by setting startTime=latestTime in the controlDict and running couplePatches. It will tell you that the ordering is correct or not (and attempt to correct the ordering and write a mesh). It will only work correctly if the two halves of the cyclic are not connected.

OpenFoam does not really make a difference between the rotational and translational; it works out a transformation tensor from the normals on the two patches.
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Old   April 21, 2005, 05:13
Default Hi Mattjis, I tried the too
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Hi Mattjis,

I tried the tool couplePatch with lots of error messages, like:
Please use topological matching or adapt the featureCos() setting
Continuing with incorrect face ordering from now on!
cyclicPolyPatch::order : Found 0 on patch cyc_ring where the cos of the angle between two connected faces was less than 0.9
cyclicPolyPatch::order : Writing zone 0 face centres to OBJ file "cyc_ring_zone_0.obj"
cyclicPolyPatch::order : Writing zone 1 face centres to OBJ file "cyc_ring_zone_1.obj"
cyclicPolyPatch::order : Number of faces per zone:2{30}


I think OpenFoam does not know whether the angle between the patches is 0 deg or 180 deg. Can I somehow define this angle (with featureCos() setting?)?
You also said :"It will only work correctly if the two halves of the cyclic are not connected."
What do you mean by It? couplePatches? Are in a rotational case the two halves of cyclic not always connected ?

Thank you!
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Old   April 21, 2005, 05:40
Default Correct. It tries to divide yo
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Correct. It tries to divide your single patch into two halves base either on
- connectivity: a translational patch will have two disconnected regions
or on
- angle between connected faces.

In your case a) does not work since I assume it is one single region and b) does not work since the angle is 0 everywhere.

Either make your case less than 180 degrees or split the patch into two regions (by introducing a tiny (or even 0) gap between the two regions)
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Old   April 21, 2005, 06:03
Default The problem is I can't make my
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The problem is I can't make my angle less than 180 deg. If I do so my "symmetry" is broken.

But If I split the pach into two regions with a tiny gap, the pach won't be connected and be treaded as translational pacht (as I understand it). This also not correct in my case!

Any suggestions? Can't I predefine an angle?

Thanks!
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Old   April 21, 2005, 06:11
Default The patch will not be treated
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The patch will not be treated as a translational patch. All cyclics are treated the same, all scalars are exchanged as is and all vectors are rotated by the rotation vector (derived from the normals).
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Old   April 21, 2005, 06:11
Default How could I use a cyclic bound
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How could I use a cyclic boundary for an annular gap? Here are the two regions also disconnected, but a translational patch would produce the wrong results!
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Old   April 21, 2005, 06:32
Default In my case there are more than
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In my case there are more than 1 one cyclic patch. For some the regions are connected (->causes the problem that OpenFoam doesn't know if the angle is 0 deg or 180 deg) and some are disconnected. In my case all scallars AND all vectors are exchanged as is (there is no rotation at all).
So I think OpenFoam calculates the wrong rotation vector.

My qyestion is:
Can this vector be influence by user input?

Thanks Mattijs!
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Old   April 21, 2005, 06:41
Default No. But you have full sour
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No.

But you have full source code ;-)

Look for calcTransformTensors in coupledPolyPatch.C and put some Info statements in there to figure out what it is doing.
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Old   April 21, 2005, 07:31
Default Ok I will have a look, allthou
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Ok I will have a look, allthough I am a C++ beginner.

Thanks anyway!
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Old   April 21, 2005, 08:37
Default It is realy hard for a beginne
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It is realy hard for a beginner to understand the code;-(.

1) Am I right that the default matching method is geometric?
2) Could I use topological matching for my problem?
3) What means featureCos()setting? And how to adapt it?
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Old   April 21, 2005, 13:49
Default 1) yes 2) no. since the start
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1) yes
2) no. since the starting ordering is invalid
3) this is the (cosine of the) angle between two neighbouring faces. If you have e.g. a 45 degree wedge like geometry with a cyclic it uses this angle to split the cyclic patch into two regions.

To change: add to couplePatches.C

after

coupledPolyPatch::setGeometricMatch(true);

the line

cyclicPolyPatch::setFeatureCos(ddd)

and add a #include "cyclicPolyPatch.H" to the top of the file.

(ddd is the cosine of the angle where you want to split the region. Note that this does not work for a 180 degree cyclic where the faces are perfectly aligned)

(And yes it is hard stuff. There are still problems with it)
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Old   April 26, 2005, 09:07
Default I have to pass. This is to com
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I have to pass. This is to complex for me. Is there somebodey in the OpenFoam communiy, who solved the problem with the 180 degree cyclic boundary - Andrew maybe or Mattijs. Or maybe someone is planning to implement it?

Best regards!
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Old   April 26, 2005, 09:07
Default I have to pass. This is to com
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I have to pass. This is to complex for me. Is there somebody in the OpenFoam communiy, who solved the problem with the 180 degree cyclic boundary - Andrew maybe or Mattijs. Or maybe someone is planning to implement it?

Best regards!
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Old   April 26, 2005, 14:14
Default Hi Duderino, I never had th
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Hi Duderino,

I never had the need for 180 degree cyclics. As said part of the problem is that there is no gap between the two halves.
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Old   November 14, 2008, 06:00
Default Hello could someone tell me
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emilianyassenov
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Hello

could someone tell me what is doing cyclic?

best regards

Emo
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