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-   -   cyclic boundary condition (http://www.cfd-online.com/Forums/openfoam-meshing/116023-cyclic-boundary-condition.html)

amit_100 April 11, 2013 07:36

cyclic boundary condition
 
can any one given some basic insite of cyclic boundary condition? :confused:

bscphil April 18, 2013 18:28

Hey Amit,

the cyclic boundary condition is a periodic boundary condition. This is usually use to reduce the mesh size of a rotationally symmetrical domain by cutting-out a piece (e.g for a 360 degree tube, you can only cut a 10 degree piece and set at the cutting planes the cyclic boundary condition).
This is for flows that are in a static sense constant in one direction, then you can set the periodic boundary conditions in these direction (p=zeroGradient @ cyclics, i think ?).

One example is e.g. a axial compressor stage grid... or this http://www.adina.com/newsgH75.shtml

mohammad81 July 4, 2013 23:31

Cyclic BC for Cavity problem
 
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.


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