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Calculating Interface Area with InterFoam

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Old   August 23, 2007, 15:47
Default Hello, I am interested in i
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Vinay Ramohalli Gopala
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Hello,

I am interested in implementing Mass and Heat transfer across the interface using VOF (interFoam solver), which requires an accurate description of the interfacial area in each cell. Can someone suggest a way to calculate the interfacial area using the present interFoam VOF implementation?

Thanks in advance,
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Old   August 24, 2007, 05:58
Default Hi Vinay Check out this li
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Hi Vinay

Check out this link in the forum

http://www.cfd-online.com/OpenFOAM_D...ges/1/172.html

Regards
Jaswinder
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Old   February 26, 2009, 07:34
Default The links seems to be dead. C
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Fabian Roesler
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The links seems to be dead.
Can anybody post the correct link of the discussion?
Thanks allot in advance.

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Fabian
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Old   February 17, 2010, 10:32
Default interface area
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Roman Thiele
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Did you ever find a solution to the problem of calculating the interface area within the cell?
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Old   July 31, 2010, 05:34
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hi friends
did you find any way to calculate interface area ?
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Old   July 31, 2010, 08:25
Default never found one
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Hej,

I tried finding a solution, but I in the end created a model to simulate and predict the size of the interface area. I assumed that the size of the cell is regular. Then calculated the area that is double diagonal within the a regular cell (in this case a cube then) and varied the size of the interface area with the amount of alpha1 within the cell, max at 0.5 alpha1 and full size of the double diagonal area.

Of course this can be made better. Additional information that can be used within such a model can be the velocity, the angle at which the interface is within the cell and the irregularity of the cell.
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Old   July 31, 2010, 10:36
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hi roman
could you please describe ur method step by step or mathematically because i didnt get what you said it was ambiguous for me

thanks in advance
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Old   July 31, 2010, 10:50
Default mathematical method
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assume a regular cell. in the case of a hexahedral cell this means, a cube with sides of length a. This length is obtainable by using the volume of a cell,V , and taking the third root.

You can put a plane diagonally through the cube. The size of this plane is given by

Amax =√(3) * V^(2/3)

When the cell is now filled with phase 1, you can read the alpha1 value. The maximum area, Amax, is now varied based on the alpha1 value. with

A = Amax*2 * alpha1; 0 ≤ α < 0.5
A = Amax*2(1-alpha1); 0.5 ≤ α ≤ 1


The code that I used for this is

Code:
Foam::tmp<Foam::volScalarField>
Foam::phaseChangeTwoPhaseMixtures::AlbaNovaInterface::interfaceArea() const
{
    // return the interfacial area based on model for interfacial area
    // returns dimensions Area

    // model based on regular volume cells, taking the largest cut area
    // as maximum for area, linear increase and decrease with alpha
    const volScalarField& cellVolume =
        alpha1_.db().lookupObject<volScalarField>("cellVolu");
    volScalarField limitedAlpha1 = min(max(alpha1_, scalar(0)), scalar(1));

    const dimensionedScalar
            areaFactor("areaFactor",dimensionSet(0,2,0,0,0,0,0), 0.0);

    volScalarField interfaceArea = alpha1_ * areaFactor;
    volScalarField maxArea = alpha1_ * areaFactor;

    maxArea = sqrt(3.0)*pow(cellVolume,(2.0/3.0));
    return tmp<volScalarField>
    (
      (neg(limitedAlpha1-0.5)*maxArea*2.0*limitedAlpha1) +
        (pos(limitedAlpha1-0.5)*maxArea*(-2.0*( limitedAlpha1 - 1.0)))
    );

}
I know that the code is not the cleanest and strictest code. For example at the part where the field with the interface areas are created, but it was at a time I didn't know too much yet :-)
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Last edited by romant; July 31, 2010 at 16:36. Reason: missing factor in calculation for the area
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Old   August 1, 2010, 02:53
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thank roman but could please tell me how could u get "cellVolu" in ur code ?
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Old   August 1, 2010, 05:29
Default create an accessible volume field
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Hej,

I created a volume field in createFields.H

Code:
// create access for cell volumes during runtime
    // needed by AlbaNovaInterface

    volScalarField cellVolu
    (
    IOobject
       (
        "cellVolu",
        runTime.timeName(),
        mesh,
        IOobject::NO_READ,
        IOobject::NO_WRITE
       ),
        mesh,
    dimensionedScalar("zero", dimVolume, 0.0)
    );
    cellVolu.internalField() = mesh.V();
this is now available throughout the runtime. It is never written, but is readable.
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