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Unknown temperature increase in cube (OpenFoam)- Help is welcomed

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Old   April 11, 2017, 11:21
Default Unknown temperature increase in cube (OpenFoam)- Help is welcomed
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Sergio López Sánchez
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Good afternoon.

I am a student from Industrial Engineering and I am doing my degree project with OpenFoam. I am new in this world.
My idea was to make a cube of air and insert (as boundaries conditions) a floor at 270 K (Kelvin), a ceiling at 330 K and the rest a 300 K. The solver I am using is buoyantPimpleFoam (compressible case).
Firstly, when I simulate it, it appears a temperature gradient through the height of the cube.

However, I want to insert an air flow (input) because the aim of the project is an HVAC application. When I add to the velocity of floor condition U (0,1,0) [that is upwards], the temperature increases a lot and I don't know exactly why. Might it be due to the pressure increase? In addition, the simulation ended before and this message appeared:
Code:
--> FOAM FATAL IO ERROR: 
wrong token type - expected Scalar, found on line 0 the word 'nan'
file: C:/OpenFOAM/user-3.0.x/run/hotRoom/v9/system/data.solverPerformance.p_rgh at line 0.

    From function operator>>(Istream&, Scalar&)
    in file lnInclude/Scalar.C at line 93.

FOAM exiting
Can anyone help me?
Thank you.

ATTACHMENTS

[/CODE]hotRoom with U velocity and Temperature increase.zip

hotRoom without U.zip



T.org file:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.x                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 300;

boundaryField
{
    floor
    {
        type            fixedValue;
        value           uniform 270;
    }

    ceiling
    {
        type            fixedValue;
        value           uniform 330;
    }

    fixedWalls
    {
        type            zeroGradient;
    }
}

// ************************************************************************* //
U file:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.x                                 |
|   \\  /    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
{
    floor
    {
        type            fixedValue;
        value           uniform (0 1 0);
    }

    ceiling
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }

    fixedWalls
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
}

// ************************************************************************* //
[CODE]p_rgh file:

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.x                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 1e5;

boundaryField
{
    floor
    {
        type            fixedFluxPressure;
        value           uniform 1e5;
    }

    ceiling
    {
        type            fixedFluxPressure;
        value           uniform 1e5;
    }

    fixedWalls
    {
        type            fixedFluxPressure;
        value           uniform 1e5;
    }
}

// ************************************************************************* //
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Old   April 13, 2017, 17:03
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Bloerb will become famous soon enough
You have one inlet and no outlet. The simulation hence crashes. Pumping air into a room without an outlet can only lead to compression of that air. and hence a temperature and pressure increase. This becomes unstable very fast and pressure and temperature reach unphysical values.
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Old   April 29, 2017, 16:20
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Sergio López Sánchez
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Quote:
Originally Posted by Bloerb View Post
You have one inlet and no outlet. The simulation hence crashes. Pumping air into a room without an outlet can only lead to compression of that air. and hence a temperature and pressure increase. This becomes unstable very fast and pressure and temperature reach unphysical values.

And how do I do that? Which conditions?
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