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, 06:18 Re #3 Senior Member   mohamed khedr emam Join Date: Oct 2011 Location: Egypt Posts: 121 Rep Power: 14 I'm now face the same problem could any one pls, tell me how to fix this problem

 March 16, 2012, 12:29 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, 21:20
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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, 21:39 #6 New Member   Snail Join Date: Mar 2012 Posts: 9 Rep Power: 14 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, 03:46 #7 New Member     Kyle Morse Join Date: Apr 2011 Location: Georgia, USA Posts: 6 Rep Power: 15 *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. blgypeng, amin.z, Chong070940103 and 2 others like this.

May 12, 2013, 08:16
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ALj89
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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 Senior Member   Join Date: Nov 2011 Posts: 109 Rep Power: 14 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: 17 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, 22:09
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

 April 9, 2016, 20:01 #12 New Member     Suyash Sharma Join Date: Feb 2016 Posts: 7 Rep Power: 10 I faced the same problem and just swapped the shadow region with periodic region and the periodic zone was successfully created.

 March 6, 2017, 10:52 #13 New Member   luiscssz Join Date: Sep 2013 Posts: 3 Rep Power: 12 Hi everyone, in my case I have resolved the problem making higher the tolerance (from 0.05 to 0.1). I think the problem comes from the CAD geometry. If the periodic domains from the CAD software are not clean (that means, there are overlapping between the periodic elements), fluents doesn´t like it and appears the error. If you increase the tolerance value (grid/modify-zone/mt), fluent doesn´t take into account this ovelapping. Bye luiscssz

March 25, 2017, 10:58
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Have a nice time!
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Quote:
 Originally Posted by AbolfazlJalalabadi 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
Hello, I followed your command and I got
what should I do?
Thanks

March 25, 2017, 11:08
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This is my impeller and I want to make periodicity in fluent..Thanks
Attached Images
 1.JPG (30.1 KB, 45 views)

 September 17, 2018, 06:40 #16 New Member   Kunal Join Date: Aug 2018 Posts: 1 Rep Power: 0 How to do that in ICEM CFD?

 September 19, 2018, 13:19 #17 Senior Member   Have a nice time! Join Date: Feb 2016 Location: mech.eng.ahmedmansour@gmail.com Posts: 291 Rep Power: 11 Hello, try this technique easier than ICEM, Thanks! https://youtu.be/eD0nxctN_yw

February 17, 2019, 12:56
#18
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Mehmet
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Quote:
 Originally Posted by luiscssz Hi everyone, in my case I have resolved the problem making higher the tolerance (from 0.05 to 0.1). I think the problem comes from the CAD geometry. If the periodic domains from the CAD software are not clean (that means, there are overlapping between the periodic elements), fluents doesn´t like it and appears the error. If you increase the tolerance value (grid/modify-zone/mt), fluent doesn´t take into account this ovelapping. Bye luiscssz
I followed your suggestion,but the fluent is still failing to create the periodicity. Do you have any further suggestions? My analysis is on 2D rotor-stator translational simulation as seen in the png. files below.

Attached Images
 fluent.jpg (112.0 KB, 48 views) rotor-stator sliding mesh.png (57.1 KB, 29 views)

 February 18, 2019, 04:43 #19 Member   Join Date: Mar 2016 Posts: 73 Rep Power: 10 Is your flow direction axis defined correctly in your "Cell Zone Conditions". If your direction axis is wrong, fluent wont be able to create a periodic boundary condition. Hint: If your mesh is periodic, fluent should detect it on it's own.

 February 19, 2019, 03:13 #20 Senior Member   Lukas Fischer Join Date: May 2018 Location: Germany, Munich Posts: 117 Rep Power: 8 In ANSYS R 18.2 for translational cyclic boundary condition I used the command line of Fluent to create it, following the description of https://www.researchgate.net/post/Ho...actually_means /mesh/modify-zones> make-periodic Periodic zone [()] 25 Shadow zone [()] 26 Rotational periodic? (if no, translational) [yes] no Create periodic zones? [yes] yes Auto detect translation vector? [yes] no x-direction (m) [0] 0 y-direction (m) [0] -0.0273 z-direction (m) [0] 0 translation deltas: 0.000000 -0.027300 0.000000 zone 26 deleted created periodic zones. Hint: Fluent tried to compute the delta in y-direction itself but calculated a value of -0.02731. The creation of the periodic zones failed during auto detect. Hence, I just entered the correct offset myself (Auto detect translation vector? [yes] no) and it worked.

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