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Hydrostatic Pressure in a cube

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Old   November 25, 2012, 08:20
Default Hydrostatic Pressure in a cube
  #1
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Dear Foamers,

I would like to understand how to implement hydrostatic pressure on a wall. I am a beginner with OF.

For that, I created a simple cube mesh:
Code:
convertToMeters 1;

vertices
(
    (0 0 0)
    (0 0 1)
    (0 1 1)
    (0 1 0)
    (1 0 0)
    (1 0 1)
    (1 1 1)
    (1 1 0)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (40 40 40) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    walls
    {
        type wall;
        faces
        (
            (0 1 2 3)
            (4 5 6 7)
        (4 0 1 5)
        (5 6 2 1)
        (7 6 2 3)
        (4 7 3 0)
        );
    }
);
I want the hydrostatic pressure, so I used buoyantPressure for p:

Code:
dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{

    walls
    {
        type            buoyantPressure;
    value        uniform 0;
    }


}
The velocity type is pressureInletVelocity and the value is uniform(0 0 0).

I also created a g folder in "constant":

Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       uniformDimensionedVectorField;
    location    "constant";
    object      g;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -2 0 0 0 0];
value           ( 0 0 -9.81 );
The fluid is not supposed to move since it is a closed cube.
I don't know exactly what solver should I use but it seems that pisoFoam is ok.

So here is the fvSolution:

Code:
solvers
{
    p
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-06;
        relTol          0;
    }

    U
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0;
    }
}

PISO
{
    nCorrectors     2;
    nNonOrthogonalCorrectors 0;
    pRefCell        0;
    pRefValue       0;
}
And for the fvSchemes, I used an existing one:

Code:
ddtSchemes
{
    default         Euler;
}

gradSchemes
{
    default         Gauss linear;
    grad(p)         Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)      Gauss linear;
}

laplacianSchemes
{
    default         none;
    laplacian(nu,U) Gauss linear corrected;
    laplacian((1|A(U)),p) Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
    interpolate(HbyA) linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p               ;
}
Here are the TransportProperties:
Code:
nu              nu [ 0 2 -1 0 0 0 0 ] 0.01;
transportModel    Newtonian;
Here is the terminal response:
Code:
--> FOAM FATAL IO ERROR: 
keyword div((nuEff*dev(T(grad(U))))) is undefined in dictionary "/home/ubuntu/openfoam/simu/cube/system/fvSchemes::divSchemes"
I don't know what model should I use for div((nuEff*dev(T(grad(U))))?
Or maybe it is a wrong solver for a simple case like that?
Thank you for your help!
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Old   November 25, 2012, 16:53
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  #2
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Florian
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I don't know if pisoFoam is right solver for this kind of problem.

For the error message you posted, simple add this expression to the divSchemes dictionary or set a default entry, e.g.
Code:
divSchemes 
{     
    default         Gauss linear;
    div(phi,U)      Gauss linear;
    div((nuEff*dev(T(grad(U))))) Gauss linear;
 }
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Old   November 26, 2012, 04:42
Default
  #3
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Thank you for your answer!

I added that line in the fvSchemes, as well as the
Code:
laplacian(nuEff,U)    Gauss linear corrected;
in the laplacianSchemes.

Still, the terminal doesn't find the "g" folder:
Code:
--> FOAM FATAL ERROR: 

    request for uniformDimensionedVectorField g from objectRegistry region0 failed
    available objects of type uniformDimensionedVectorField are

0
(
)
Where is the objectRegistry region0?
I tried to copy/paste the g in all the folders (0,constant,system) still doesn't work.

Thanks for your help!
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