[Danath]

If you convert your case from Fluent where you define the the cyclic boundary conditions .(Needless blockMeshDic)

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?

[mohammad81]

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.

[desert_1250]

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<scalar> 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

[vahidshahabi]

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.

[nimasam]

use AMIcyclic,instead, it may solve your problem

[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

[Persia]

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.

[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?

[Persia]

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?

[majid pourdian]

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.

[majid pourdian]

Hi esmaeil
your neighbour patch should have equal area and mesh.