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-   -   cyclic boundary conditions for airfoil (https://www.cfd-online.com/Forums/openfoam-pre-processing/107852-cyclic-boundary-conditions-airfoil.html)

A.Wendy October 8, 2012 05:41

cyclic boundary conditions for airfoil
 
1 Attachment(s)
Hi,

i am trying to do some cyclic calculation for an foil of an helicopter and want to use cyclic boundaries.

the plan is, to the outlet after the foil for the inlet in front of the foil. but how can i realise that?
i changed the boundary files as follows:

Quote:

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM Extend Project: Open source CFD |
| \\ / O peration | Version: 1.6-ext |
| \\ / A nd | Web: www.extend-project.de |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class polyBoundaryMesh;
location "constant/polyMesh";
object boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

10
(
sides
{
type wall;
nFaces 0;
startFace 13865;
}
originalPatch
{
type patch;
nFaces 0;
startFace 13865;
}
otherSide
{
type patch;
nFaces 0;
startFace 13865;
}
bottom
{
type patch;
nFaces 50;
startFace 13865;
}
outlet
{
type cyclic;
nFaces 50;
startFace 13915;
matchTolerance 0.001;
neighbourPatch bottom;
}
top
{
type patch;
nFaces 50;
startFace 13965;
}
inlet
{
type cyclic;
nFaces 50;
startFace 14015;
matchTolerance 0.001;
neighbourPatch bottom;
}
profil
{
type wall;
nFaces 982;
startFace 14065;
}
front
{
type empty;
nFaces 6955;
startFace 15047;
}
back
{
type empty;
nFaces 6955;
startFace 22002;
}
)
but how do i have to set the starting parameters for the velocity? i want to get cw-values and have to create an airspeed?

i attached a picture of the mesh.

with regards

Andy

ngj October 8, 2012 05:46

Hi Andy,

You would need to either apply a body force in the solver, or maybe (I have not used it), use one of the jumpCyclic boundary conditions. This should allow you to have a jump in the pressure across the cyclic boundary, which will drive the current.

With respect to adding a body force in the solver, you will be able to find discussions on this forum.

Kind regards,

Niels

amin144 October 8, 2012 06:36

Quote:

Originally Posted by ngj (Post 385478)
Hi Andy,

You would need to either apply a body force in the solver, or maybe (I have not used it), use one of the jumpCyclic boundary conditions. This should allow you to have a jump in the pressure across the cyclic boundary, which will drive the current.

With respect to adding a body force in the solver, you will be able to find discussions on this forum.

Kind regards,

Niels

Dear Niels

Can you introduce me any thread about adding body force to solver in order to use cyclic boundary condition?
I've read and ran channel foam tutorial but I can't use cyclic boundary condition for my solver.
My case in a pipe which I want simulate one cross section of that in a fully developed state.

TanX very much


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