[Bob!]

Hey guys,

I'm trying to run an as i think quite simple case - still it ain't working.
I've got a rectangular U-Pipe with an incompressible, turbulent flow of water.
Beside the geometric details i only got the Volume which flows in and with it of course the velocity.
I'm using simpleFoam, k-Epsilon-model, RAS.
blockMesh works, simpleFoam runs without an error.
My Problem is, that the velocity doesn't work well. I've git a fixed "inlet-Velocity" of 0.3339 m/s but when viewing with ParaView, i get a velocity of 0.001 (or something small like this) after the first time step.

I made a lot of suggestions about the correct BCs and tried as much as i could by try and error- still i got this problem.
Another suggestion of mine was, that the "internal faces", which are "connecting"/between the five blocks of which the U-Pipe consists, are false defined- but as i read: there doesn't have to be any special definition, they're flowing through automatically. When viewing "p" in ParaView, it's possible to see the change through the complete Pipe - this is why i think that ain't the problem. (When modelling a straight pipe, out of one Block, there ain't a Problem [same BCs etc])

So there must be something wrong with my BCs- and as i said, i tried a lot of different BCs and ain't got any more ideas. I hope, that someone else can help me out and has a better idea...

I'm posting a version of my case, of which i thought it might have worked.
Thanks in advance for any ideas which even might help!!!


Code:

     /*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{

    inlet
    {
        type    fixedValue;
    value    uniform (0 0 -0.3338675216);
    }

    outlet
    {
        type            zeroGradient;
    }

    fixedWalls
    {
        type            noSlip;
    }

}

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

     /*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{

    inlet
    {
    type        zeroGradient;
    }

    outlet
    {
        type            fixedValue;
        value           uniform 0.2045380588;
    }

    fixedWalls
    {
        type            zeroGradient;
    }

}

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

     /*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
    (0 0 0) //0
    (26 0 0) //1
    (26 16 0) //2
    (0 16 0) //3
    (0 0 -1938) //4
    (26 0 -1938) //5
    (26 16 -1938) //6
    (0 16 -1938) //7
    (0 0 -1968) //8
    (26 0 -1968) //9
    (26 16 -1968) //10
    (0 16 -1968) //11
    (246 0 -1968) //12
    (274 0 -1968) //13
    (274 16 -1968) //14
    (246 16 -1968) //15
    (246 0 -1938) //16
    (274 0 -1938) //17
    (274 16 -1938) //18
    (246 16 -1938) //19
    (246 0 0) //20
    (274 0 0) //21
    (274 16 0) //22
    (246 16 0) //23
);

blocks
(
    hex (4 5 6 7 0 1 2 3) (10 10 20) simpleGrading (1 1 1)
    hex (8 9 10 11 4 5 6 7) (10 10 20) simpleGrading (1 1 1)
    hex (9 12 15 10 5 16 19 6) (10 10 20) simpleGrading (1 1 1)
    hex (12 13 14 15 16 17 18 19) (10 10 20) simpleGrading (1 1 1)
    hex (16 17 18 19 20 21 22 23) (10 10 20) simpleGrading (1 1 1)
);

edges
(
);

boundary
(

    
    fixedWalls
    {
        type wall;
        faces
        (
            (2 3 7 6)
            (3 0 4 7)
            (0 1 5 4)
            (1 2 6 5)

            (6 7 11 10)
            (7 4 8 11)
            (4 5 9 8)

            (5 6 19 16)
            (19 6 10 15)
            (12 15 10 9)
            (5 16 12 9)

            (15 14 18 19)
            (18 14 13 17)
            (16 17 13 12)

            (22 23 19 18)
            (23 20 16 19)
            (20 21 17 16)
            (21 22 18 17)

        );
    }

    inlet
    {
        type patch;
        faces
        (
            (0 3 2 1)     
        );
    }

    outlet
    {
        type patch;
        faces
        (
            (20 23 22 21)
        );
    }
);

mergePatchPairs
(
);

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

[verboomj]

Is your inlet faced towards the -Z direction as your velocity?
Could you try and set the pressure to 0 and leave the velocity?
Try running it with Turbulence off;

Hope you find whats wrong.

[Bob!]

Hey

thanks a lot for the reply!
The inlet should be fine and - however (because i definitely tried before)- you were right with your pressure assumption! It works and it works well as it seems to me =)
Wouldn't have tried it again without your comment - thanks a lot!