BC on flow around a square?

Wizze · September 29, 2014, 14:34

Hey everyone

I am trying to simulate a flow around a square using icoFoam. I can't figure out what my boundary conditions are supposed to be. Any suggestions on how i should do it? I have tried to depict my case in the attached picture. I have created my mesh by using ICEM.

I am getting the "Floating point exception (core dumped)" error.

Code:

/*--------------------------------*- 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       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    TOP
    {
        type            slip;

    }

    OUTLET
    {
        type            fixedValue;
	value		uniform 0;
    }

    BOTTOM
    {
        type            slip;
    }
    INLET
    {
        type            zeroGradient;
    }
    WALL
    {
        type            zeroGradient;
    }
}

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

Code:

/*--------------------------------*- 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       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (0 0 0);

boundaryField
{
    TOP
    {
        type            slip;

    }

    OUTLET
    {
        type            zeroGradient;
    }

    BOTTOM
    {
        type            slip;
    }
    INLET
    {
        type            fixedValue;
	value		uniform (10 0 0);
    }
    WALL
    {
        type            fixedValue;
	value		uniform (0 0 0);
    }
}

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

mohsen cheraghi · September 30, 2014, 12:15

Quote:

Originally Posted by Wizze

Hey everyone

I am trying to simulate a flow around a square using icoFoam. I can't figure out what my boundary conditions are supposed to be. Any suggestions on how i should do it? I have tried to depict my case in the attached picture. I have created my mesh by using ICEM.

I am getting the "Floating point exception (core dumped)" error.

Code:

/*--------------------------------*- 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       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    TOP
    {
        type            slip;

    }

    OUTLET
    {
        type            fixedValue;
	value		uniform 0;
    }

    BOTTOM
    {
        type            slip;
    }
    INLET
    {
        type            zeroGradient;
    }
    WALL
    {
        type            zeroGradient;
    }
}

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

Code:

/*--------------------------------*- 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       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (0 0 0);

boundaryField
{
    TOP
    {
        type            slip;

    }

    OUTLET
    {
        type            zeroGradient;
    }

    BOTTOM
    {
        type            slip;
    }
    INLET
    {
        type            fixedValue;
	value		uniform (10 0 0);
    }
    WALL
    {
        type            fixedValue;
	value		uniform (0 0 0);
    }
}

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

Hi, you shoud change the BC of pressure on the top and bottom to zeroGradient.

Wizze · September 30, 2014, 12:20

How come? I want the top and bottom to not have the non-slip condition (so the square I am investigating doesn't get affected by this) , hence I have slip as a BC. Does slip only work for velocity since you are only suggesting me to change the pressure BC?

mohsen cheraghi · September 30, 2014, 12:25

Quote:

Originally Posted by Wizze

How come? I want the top and bottom to not have the non-slip condition (so the square I am investigating doesn't get affected by this) , hence I have slip as a BC. Does slip only work for velocity since you are only suggesting me to change the pressure BC?

I think slip condition for v and zeroGradient for P is OK.

Wizze · September 30, 2014, 12:28

Could you please explain in detail? :-)

mohsen cheraghi · September 30, 2014, 12:32

Slip BC is defined for velocity. it considers zero gradient for tangential component and zero value for normal component. But, for pressure as a scalar field, you should put zeroGradient.

Wizze · September 30, 2014, 12:35

Still not working. I suspect something is wrong in my fvschemses and fvsolution files. I just used what I found in the icoFoam cavity tutorial. Any suggestions?

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September 30, 2014, 12:20		#3
Wizze New Member Join Date: Sep 2014 Posts: 12 Rep Power: 12	How come? I want the top and bottom to not have the non-slip condition (so the square I am investigating doesn't get affected by this) , hence I have slip as a BC. Does slip only work for velocity since you are only suggesting me to change the pressure BC?

September 30, 2014, 12:28		#5
Wizze New Member Join Date: Sep 2014 Posts: 12 Rep Power: 12	Could you please explain in detail? :-)

September 30, 2014, 12:32		#6
mohsen cheraghi New Member mohsen cheraghi Join Date: Jun 2010 Location: Switzerland Posts: 28 Rep Power: 16	Slip BC is defined for velocity. it considers zero gradient for tangential component and zero value for normal component. But, for pressure as a scalar field, you should put zeroGradient.

September 30, 2014, 12:35		#7
Wizze New Member Join Date: Sep 2014 Posts: 12 Rep Power: 12	Still not working. I suspect something is wrong in my fvschemses and fvsolution files. I just used what I found in the icoFoam cavity tutorial. Any suggestions?