# periodic boundaries

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 September 21, 2005, 03:52 periodic boundaries #1 Mary Guest   Posts: n/a I want to define two rotational periodic boundaries (the angle between them is 180°). They are identically (equal number of faces, equal geometry). /grid/modify-zones> make-periodic Periodic zone [()] 5 Shadow zone [()] 7 Rotational periodic? (if no, translational) [yes] yes Create periodic zones? [yes] yes zone 5: matched 13596 out of 15234 faces. zone 7: matched 13596 out of 15234 faces. Error: Failed to make zones periodic. Error Object: #f Can someone help me ??

 September 26, 2005, 13:13 Re: periodic boundaries #2 KHAN Guest   Posts: n/a can u specify the details of the geometry, then we can discuss about the problem - thanks!

 February 25, 2012, 07:18 Re #3 Senior Member   mohamed khedr emam Join Date: Oct 2011 Location: Egypt Posts: 121 Rep Power: 5 I'm now face the same problem could any one pls, tell me how to fix this problem

 March 16, 2012, 13:29 Re: periodic boundaries #4 New Member   Dan Barnett Join Date: Mar 2012 Posts: 1 Rep Power: 0 Has anyone determined a solution to this problem in Fluent? I also am working on simulations that require rotational periodicy. Occasionally I am able to create the periodic zones, but sometimes I receive the errors: "Error: Failed to make zones periodic. Error Object: #f" I believe that I am not doing anything different when I create the periodic zone successfully. I am always ensuring that the rotational axis is aligned with the z-axis of the geometry and I am using match control in meshing for the two faces of the periodic zone. Any ideas of what may casue this?

March 16, 2012, 22:20
#5
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mohamed khedr emam
Join Date: Oct 2011
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Quote:
 Originally Posted by dbarnett Has anyone determined a solution to this problem in Fluent? I also am working on simulations that require rotational periodicy. Occasionally I am able to create the periodic zones, but sometimes I receive the errors: "Error: Failed to make zones periodic. Error Object: #f" I believe that I am not doing anything different when I create the periodic zone successfully. I am always ensuring that the rotational axis is aligned with the z-axis of the geometry and I am using match control in meshing for the two faces of the periodic zone. Any ideas of what may casue this?
yes i solved it before,
Type in Fluent command Window
>Mesh
>mp if doesn't work try to type the following and change number
>Mesh
>Mz
>Mt "change value (limit is 0.5)"

 March 17, 2012, 22:39 #6 New Member   Snail Join Date: Mar 2012 Posts: 9 Rep Power: 5 i faced the same problem. maybe u shoud make periodic in your meshing software ，then export the grid，at last import into FLUENT、、、、、、、which meshing software you are useing？？ICEM CFD can do it.

 December 14, 2012, 04:46 #7 New Member     Kyle Morse Join Date: Apr 2011 Location: Georgia Southern University Posts: 6 Rep Power: 6 *I know I am late but, you must have the axis of rotation in the global z-direction for rotational periodicity. It may also be true that translational periodicity must be orthogonal across z as well. Use /mesh/rotate in the interpreter and set your point of origin and axis of mesh rotation so that the global z-axis is parallel with the axis of periodicity use /mesh/mz/make-periodic in the interpreter and move on as usual. You can also invoke periodicity in your meshing software (* Z-axis and axis of periodicity must be parallel) and Fluent should take care of it from there. If there is a way to make the stored axis something other than (0 0 1) or any other vector, none of the above would matter. amin.z and Chong070940103 like this.

May 12, 2013, 08:16
#8
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Quote:
 Originally Posted by Mary ;124397 I want to define two rotational periodic boundaries (the angle between them is 180°). They are identically (equal number of faces, equal geometry). /grid/modify-zones> make-periodic Periodic zone [()] 5 Shadow zone [()] 7 Rotational periodic? (if no, translational) [yes] yes Create periodic zones? [yes] yes zone 5: matched 13596 out of 15234 faces. zone 7: matched 13596 out of 15234 faces. Error: Failed to make zones periodic. Error Object: #f Can someone help me ??
Hi
The default tolerance can be problematic in small meshes

just use the text command
grid/modify-zone/mt
and specify smaller tol's untill all nodes are matched up and then you're good to go
I had to reduce from 0.1 to 1e-6

 October 23, 2013, 02:52 #9 Member   Join Date: Nov 2011 Posts: 81 Rep Power: 5 I was facing the same problem and I solved it by changing the rotation axis on the "cell zone condition" tab. My geometry was rotationally periodic along x axis but standard fluent settings use the z axis as the rotation axis. I hope this helps! Cheers, Rob

 October 23, 2013, 05:58 #10 Member   vidyanand Join Date: Nov 2011 Location: bangalore,india Posts: 66 Rep Power: 8 This is problem of mesh, if you not mesh same cell size and division on periodic boundaries, Fluent through this error, If you want to avoid 1.Remesh,with match control. 2.If it irregular geometry then use periodic interface in fluent ( interface option defining boundaries as interface )

January 9, 2014, 23:09
wdxgd
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Quote:
 Originally Posted by robboflea I was facing the same problem and I solved it by changing the rotation axis on the "cell zone condition" tab. My geometry was rotationally periodic along x axis but standard fluent settings use the z axis as the rotation axis. I hope this helps! Cheers, Rob
It is useful,thanks

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