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-   -   Periodic BC rotating channel (http://www.cfd-online.com/Forums/openfoam/133037-periodic-bc-rotating-channel.html)

Jiricbeng April 9, 2014 09:14

Periodic BC rotating channel
 
Hi there,

I have ascii mesh .msh of rotor segment and another .msh of draft tube. Desired BC conditions are velocity at the inlet of the rotor and static pressure at the draft tube outlet and mixing plane between rotor and drafut tube.

I merge these meshes by using mergeMeshes but I cant figure out the correct setting of periodical conditions for the rotor faces (rotor mesh is channel with one blade - but there are five blades really). Moreover I d like to know the settings for mixing plane between this rotor segment and the draft tube.
I am using OF 2.3.0
I struggle a lot but cannot sort it out.

I am grateful for any help!

Jiricbeng April 11, 2014 05:15

I would like to prepare calculation in the following way:
- Having two separate mesh files (e.g. rotor.msh and draft_tube.msh)
- by using fluentMeshToFoam rotor.msh -writeSets a convert .msh to OF format. The same I do with draft_tube.msh.
- then merge them in OF (as I said I use mergeMeshes as I do not want to merge them in another program)
- set boundary conditions, but still I cannot find out how.

Thank you for any advice

Jiricbeng April 15, 2014 03:45

I successfully merged two regions -rotor and draft tube, however I am struggling with BC.
Rotor domain is just a rotating segment (just 90 to save mesh size).

Rotor domain is composed of:
inflow
outflow
blade
interface on hub (gap between hub and blade)
interface on shroud(gap between shroud and blade)
per1 - first side face of Rotor domain
per2 - second side face of Rotor domain

Draft tube domain (is stationary) is composed of:
wall-4 ...inlet (outlet from rotor domain)
wall-5 ...outlet (pressure outlet)
wall-3, wall-6, wall-7 are walls.

Could anyone help me please with setting BC for rotating Rotor domain? I guess the main trouble is in setting per1 and per2. I use OpenFoam 2.3.0


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class polyBoundaryMesh;
location "polyMesh";
object boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

16
(
hub
{
type wall;
inGroups 1(wall);
nFaces 3825;
startFace 2246933;
}
shroud
{
type wall;
inGroups 1(wall);
nFaces 3098;
startFace 2250758;
}
inflow
{
type patch;
nFaces 3128;
startFace 2253856;
}
outflow
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch wall-4;
zone outflow_ZONE;
transform noOrdering;
nFaces 3332;
startFace 2256984;
}
blade
{
type wall;
inGroups 1(wall);
nFaces 6254;
startFace 2260316;
}
hub-tip-ggi-side-1
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch hub-tip-ggi-side-2;
zone hub-tip-ggi-side-1_ZONE;
transform noOrdering;
nFaces 816;
startFace 2266570;
}
hub-tip-ggi-side-2
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch hub-tip-ggi-side-1;
zone hub-tip-ggi-side-2_ZONE;
transform noOrdering;
nFaces 876;
startFace 2267386;
}
shroud-tip-ggi-side-1
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch shroud-tip-ggi-side-2;
zone shroud-tip-ggi-side-1_ZONE;
transform noOrdering;
nFaces 930;
startFace 2268262;
}
shroud-tip-ggi-side-2
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch shroud-tip-ggi-side-1;
zone shroud-tip-ggi-side-2_ZONE;
transform noOrdering;
nFaces 915;
startFace 2269192;
}
per1
{
type cyclicAMI;
inGroups 1(cyclicAMI);
nFaces 3468;
startFace 2270107;
transform rotational;
neighbourPatch per2;
rotationAxis (0 0 1);
rotationCentre (0 0 0);
rotationAngle 90; // degrees
}
per2
{
type cyclicAMI;
inGroups 1(cyclicAMI);
nFaces 3468;
startFace 2273575;
transform rotational;
neighbourPatch per1;
rotationAxis (0 0 1);
rotationCentre (0 0 0);
rotationAngle 90; // degrees
}
wall-3
{
type wall;
inGroups 1(wall);
nFaces 3272;
startFace 2277043;
}
wall-4
{
type cyclicAMI;
inGroups 1(cyclicAMI);
neighbourPatch outflow;
zone wall-4_ZONE;
transform noOrdering;
nFaces 5580;
startFace 2280315;
}
wall-5
{
type patch;
nFaces 2390;
startFace 2285895;
}
wall-6
{
type wall;
inGroups 1(wall);
nFaces 6118;
startFace 2288285;
}
wall-7
{
type wall;
inGroups 1(wall);
nFaces 22156;
startFace 2294403;
}
)

// ************************************************** *********************** //

Jiricbeng April 23, 2014 05:00

any idea please?

Jiricbeng April 25, 2014 07:11

Please have a look at my files, I uploaded it here:
http://leteckaposta.cz/632363549

I would like to set periodic boundaries on per1 and per2 which are the side faces of the blade segment. When I set per1 and per2 as cyclic I cannot visualise the mesh in openfoam.

Mehrez May 23, 2014 13:16

Hi dear Jiricbeng,
To set periodic BC, you need to have the same mesh in the two faces.
You can mesh a face and then copy to another before setting the cyclic BC.
Mehrez

Quote:

Originally Posted by Jiricbeng (Post 488162)
Please have a look at my files, I uploaded it here:
http://leteckaposta.cz/632363549

I would like to set periodic boundaries on per1 and per2 which are the side faces of the blade segment. When I set per1 and per2 as cyclic I cannot visualise the mesh in openfoam.



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