[mAlletto]

Hello all,

does somebody know how to apply shifted periodic boundary conditions in OpenFOAM. Basically in periodic boundary conditions the velocity at the outflow is taken and reintroduced at the same lateral and vertical position at the inlet.

I wanted to do the same, but i want to shift the lateral position by some distance being y the lateral coordinate. x is the streamwise coordinate and z is the wall normal coordinate. The scope is to avoid an annatural long living of the streamwise streaks caused by the periodic boundary conditions.

Basically I wanted to do the same as https://www.researchgate.net/publica...urbulent_flows

Is there a way to achieve this?

Best

Michael

[mAlletto]

Maybe I can aswer the question by myself:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  5                                     |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version         2.0;
    format          ascii;
    class           dictionary;
    object          blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 1;

vertices
(
    ( -2500  -1000   0)// 0
    ( 2500  -1000   0) // 1
    ( 2500    0   0) // 2
    ( -2500   0   0) // 3
    ( -2500  -1000   4000) // 4
    ( 2500  -1000   4000) // 5
    ( 2500    0   4000) // 6
    ( -2500   0   4000) // 7

    ( -2500    1000   0) // 8
    (  2500    1000   0) // 9
    ( -2500    1000   4000) // 10
    (  2500    1000   4000) // 11


);

blocks
(
    hex (0 1 2 3 4 5 6 7) (250 50 200) simpleGrading (1 1 1)
    hex (3 2 9 8 7 6 11 10) (250 50 200) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    east1
    {
        type cyclic;
        neighbourPatch  west2;
        transform       translational;
        separationVector (-5000 1000 0);
        faces
        (
            (2 6 5 1)
        );
    }
    east2
    {
        type cyclic;
        neighbourPatch  west1;
        transform       translational;
        separationVector (-5000 -1000 0);
        faces
        (
            (2 9 11 6)
        );
    }
    north
    {
        type cyclic;
        neighbourPatch south; 
        faces
        (
            (1 5 4 0)
        );
    }
    south
    {
         type cyclic;
        neighbourPatch north;
        faces
        (
            (8 9 11 10)
        );
    }
    west1
    {
        type cyclic;
        neighbourPatch  east2;
        transform       translational;
        separationVector (5000 1000 0);
        faces
        (
            (0 4 7 3)
        );
    }
    west2
    {
        type cyclic;
        neighbourPatch  east1;
        transform       translational;
        separationVector (5000 -1000 0);
        faces
        (
            (3 8 10 7)
        );
    }
    lower
    {
        type wall;
        faces
        (
            (0 3 2 1)
            (3 2 9 8)
        );
    }
    upper
    {
        type patch;
        faces
        (
            (4 5 6 7)
            (7 6 11 10)
        );
    }
);

mergePatchPairs
(
);


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

[Tim_]

Hi, did you get any further with this. For example working out how to do it for an arbitrary number of outlet/inlet slices? or an openfoam BC that works to similar effect?