# cyclic boundary condition

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June 10, 2013, 09:30
#21
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Evangelos
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If you convert your case from Fluent where you define the the cyclic boundary conditions .(Needless blockMeshDic)
Quote:
 Originally Posted by huxiaoxia Dear HuyHoang: Sorry to reply you late. First of all, in constant/polyMesh/blockMeshDic, you have to define the cyclic boundary, e.g cyclic back ( (0 2 3 1) (6 7 9 8) ) Then , when you define all the initial or boundary conditions under the folder 0, simply use the type cyclic. e.g back { type cyclic; } Is it clear for you?

 July 4, 2013, 23:29 #22 New Member   Mohammad Join Date: Jul 2013 Posts: 10 Rep Power: 6 Hi everyone. I want to use cyclic (periodic) BC for cavity problem. it sounds simple. I want to use cyclic BC for both P and U (for inlet and outlet). I want to know what I have done is correct or not. Thank you. This is blockMeshDict: ------------------------------------------- patches ( wall topWall ( (3 7 6 2) ) wall bottomWall ( (1 5 4 0) ) cyclic inout ( (0 4 7 3) (2 6 5 1) ) empty frontAndBack ( (0 3 2 1) (4 5 6 7) ) ); ------------------------------------------- This is my Boundary file: 4 ( topWall { type wall; nFaces 40; startFace 1540; } bottomWall { type wall; nFaces 40; startFace 1580; } inout { type cyclic; nFaces 40; startFace 1620; featureCos 0.9; } frontAndBack { type empty; nFaces 1600; startFace 1660; } ) -------------------------------------- My 0/U is: inout { type cyclic; value uniform (0 0 0); } --------------------------- Finally 0/P is: inout { type cyclic; value uniform 0; } -------------- Is this correct? I got some result. I get the linear velocity and uniform pressure (Couette Flow). But I am not sure of it. Is this type of using cyclic correct? what is this "neigbourpathc", "fan" etc..? Thank you very much. hua1015 likes this.

 July 10, 2013, 04:24 #23 Member   s.rasoul_varedi Join Date: Feb 2010 Posts: 82 Rep Power: 8 Hi Dear mamad (oshtoli) i think u need fan BC. In OF the fan BC prescribes a pressure jump. Note!The fan boundary condition is working on a cyclic patch. defined in constant/polyMesh/boundary as { type cyclic; } and then in the pressure file 0/p: { type fan; patchType cyclic; f List 2(10.0 -1.0); value uniform 0; } The f above is a list of polynomial coefficients in the pressure jump definition delta p = f_1 + f_2 * v + f_3 * v^2 + ... Above only f_1 and f_2 is assigned, respectively 10.0 and -1.0. In 0/U and so on, the ad patch is defined as cyclic. any quastions are wellcome. -------- Rasoul

 October 31, 2014, 16:47 cyclic boundry condition #24 New Member   Join Date: Oct 2014 Posts: 2 Rep Power: 0 I want to simulate a channel flow in a periodically repeating geometry, the mesh generator is Gambit, I define my boundary conditions in gambit using "wall" not "periodic" or something else, after i converted the mesh with fluentMeshToFoam, in constant/polymesh/boundary i changed wall to cyclic for my periodic boundaries(inlet& outlet). As shown in blow boundaryField { outlet { type cyclic; neighbourPatch inlet; } inlet { type cyclic; neighbourPatch outlet; } wall-h { type fixedValue; value uniform 300; } wall-c { type fixedValue; value uniform 200; } frontAndBackPlanes { type empty; } } its ok, but after some times, I have following error message FOAM FATAL ERROR, attemo to cast type patch to type LduInterface FOAM aborting, foam::error:: print stack Can you tell me how i solve this issue. Thank you for your help.

 November 3, 2014, 09:59 #25 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,240 Blog Entries: 1 Rep Power: 18 use AMIcyclic,instead, it may solve your problem __________________ Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog in Persian(http://openfoam.blogfa.com/) My Personal Website (http://nimasamkhaniani.ir/)

 March 15, 2016, 06:57 dsmcFOAM BLOCKMESHDICT #26 New Member   avinash yadav Join Date: Mar 2016 Location: Almora Posts: 1 Rep Power: 0 HI I AM FACING A PROBLEM TO UNDERSTAND xPeriodic_half0 { type cyclic; faces ((1 2 6 5)); neighbourPatch xPeriodic_half1; COMMAND WHAT IS THE ACTUAL MEAN OF THIS CAN ANYBODY HELP ME

March 23, 2016, 02:53
Cyclic boundary definition
#27
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Maryam
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Quote:
 Originally Posted by avinashy34 HI I AM FACING A PROBLEM TO UNDERSTAND xPeriodic_half0 { type cyclic; faces ((1 2 6 5)); neighbourPatch xPeriodic_half1; COMMAND WHAT IS THE ACTUAL MEAN OF THIS CAN ANYBODY HELP ME
It means that "xPeriodic_half0" is a cyclic patch, which is another term for periodic BC. "xPeriodic_half0" consists of the face with corner points 1, 2, 6, and 5, and its neighbour patch is patch "xPeriodic_half1". This means that "xPeriodic_half1" and "xPeriodic_half0" will have the same values for different parameters such as velocity, pressure, or temperature.

 August 11, 2016, 17:16 cyclic Bc error #28 New Member   majid Join Date: Oct 2015 Location: Iran,Tehran Posts: 10 Rep Power: 4 Hi I have a simmulation with cyclic boundary condition and I get this error: "Error in coupled point location" when I change cyclic Bc to wall Bc error is disapeared. could anyone help me?

August 15, 2016, 01:46
#29
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Maryam
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Quote:
 Originally Posted by majid pourdian Hi I have a simmulation with cyclic boundary condition and I get this error: "Error in coupled point location" when I change cyclic Bc to wall Bc error is disapeared. could anyone help me?
Do the cyclic patches fully match geometrically?

August 15, 2016, 16:17
#30
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majid
Join Date: Oct 2015
Location: Iran,Tehran
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Quote:
 Originally Posted by Persia Do the cyclic patches fully match geometrically?
yes,I correct geometrically match error when I run blockMesh.now when I run checkMesh give me second error.

 August 16, 2016, 13:23 #31 New Member   majid Join Date: Oct 2015 Location: Iran,Tehran Posts: 10 Rep Power: 4 Hi esmaeil your neighbour patch should have equal area and mesh.

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