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Interfoam failed to solve for alpha (air-water flow in 3D pipe)

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Old   October 28, 2016, 04:11
Default Interfoam failed to solve for alpha (air-water flow in 3D pipe)
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Milad
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Guys,

I am getting so confused. I used to simulate 2D air-water two phase flow using interFoam as the solver, but recently I just switched to 3D simulation. Unfortunately I just came up with no results for alpha (volume phase fraction).
I used blockMesh to create my geometry as below:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.01;

vertices
(
(0 0 0) //0

(0.3535 0.3535 0) //1
(-0.3535 0.3535 0) //2
(-0.3535 -0.3535 0) //3
(0.3535 -0.3535 0) //4

(0.3535 0.3535 30) //5
(-0.3535 0.3535 30) //6
(-0.3535 -0.3535 30) //7
(0.3535 -0.3535 30) //8
(0 0 30) //9
);

blocks
(
hex (1 2 3 4 5 6 7 8) (10 10 150) simpleGrading (1 1 1)

);

edges
(
arc 1 2 (0 0.5 0)
arc 2 3 (-0.5 0 0)
arc 3 4 (0 -0.5 0)
arc 4 1 (0.5 0 0)

arc 5 6 (0 0.5 30)
arc 6 7 (-0.5 0 30)
arc 7 8 (0 -0.5 30)
arc 8 5 (0.5 0 30)
);

boundary
(
inlet
{
type patch;
faces
(
(1 2 3 4)
);

}

outlet
{
type patch;
faces
(
(5 6 7 8)
);
}

fixedWalls
{
type wall;
faces
(
(5 6 2 1)
(6 7 3 2)
(7 8 4 3)
(8 5 1 4)

);
}

);

mergePatchPairs
(
);

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

I was actually wondering if I did not set the proper inlet condition for alpha!

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.4.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object alpha.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type inletOutlet;
inletValue uniform 0.5;
value uniform 0.5;
}


outlet
{
type zeroGradient;
}


fixedWalls
{
type zeroGradient;
}

}

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

But just take a look at the result of alpha for example @ t=0.1s:

/*--------------------------------*- 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;
location "0.1";
object alpha.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type inletOutlet;
inletValue uniform 0.5;
value uniform 0;
}
outlet
{
type zeroGradient;
}
fixedWalls
{
type zeroGradient;
}
}


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

I appreciate if anyone could please make any comments on that.
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Old   October 28, 2016, 04:46
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Arsalan
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Hi Milad,
what did you set the inlet boundary condition for velocity? please give detailed information for a more accurate solution.
Furthermore, its better to use [CODE] tag for writing dictionaries in your thread, anyway it has a better representation.

Regards,
Arsalan.
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Old   October 28, 2016, 11:08
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Milad
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Quote:
Originally Posted by arsalan.dryi View Post
Hi Milad,
what did you set the inlet boundary condition for velocity? please give detailed information for a more accurate solution.
Furthermore, its better to use [CODE] tag for writing dictionaries in your thread, anyway it has a better representation.

Regards,
Arsalan.
Dear Arsalan

Thank you so much for your response. I used fixedVelocity for inlet U. Attached hereby, please find my case file.

Best,
Milad
Attached Files
File Type: gz pipeflow.tar.gz (3.8 KB, 28 views)
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Old   October 29, 2016, 04:20
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Brian Willis
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Hi Milad

Check your U boundary condition in your 0 time directory. The length of your pipe is along the z-direction. Your U boundary condition on the inlet is (1 0 0). Changing it to (0 0 1) should sort out your problem. I tested it out and it works with just that change.

Regards,
Brian
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Last edited by Dipsomaniac; October 29, 2016 at 05:11. Reason: spelling
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Old   October 29, 2016, 07:13
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Arsalan
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Hi Milad,

As Brian said, you should modify velocity boundary condition at inlet along the Z direction and normal to the patch (like (0,0,1)),this will solve the problem.

Regards,
Arsalan.
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Old   October 29, 2016, 07:41
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Milad
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Dear fiends Brian and Arsalan,

I really appreciate your helps. You are right and that worked.

Thank you!
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