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Curvature of the interface using interFoam

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Old   March 1, 2011, 14:16
Default Curvature of the interface using interFoam
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Andrea Ferrari
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Hi all,

I am using interFoam to simulate multiphase flow in different geometries and I tried to write a little piece of code (writeCurvature.C that i call as a post processing) to calculate the curvature of the interface following the same method that openFoam normally use in the VOF method. (the calculations that i have done are identical to those in interfaceProperties.C). The problem is that I get strange result. I expected to find high values near the interface and values close to zero in the bulk but it is not!

i attached 2 jpg. one is the colour plot of alpha1 and the other one is the colour plot of the curvature that i got.
Any suggestion?

thanks
andrea
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File Type: png alpha.png (21.7 KB, 94 views)
File Type: jpg curvature.jpg (41.9 KB, 98 views)
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Old   March 2, 2011, 05:19
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Andrea Ferrari
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someone who has any idea why I find this curvature?
These are the calculations I've done:

Code:
reading alpha1 first
then

// now calc the gradients
        volVectorField gradAlpha1 = fvc::grad(alpha1);

         Info<< "Writing gradAlpha1 to " << gradAlpha1.name() << " in "
             << runTime.timeName() << endl;

         gradAlpha1.write();


         // Interpolated face-gradient of alpha
        surfaceVectorField gradAlphaf = fvc::interpolate(gradAlpha1);


        dimensionedScalar deltaN_ =  1e-8/pow(average(alpha1.mesh().V()), 1.0/3.0);


        // Face unit interface normal
        surfaceVectorField nHatfv = gradAlphaf/(mag(gradAlphaf) + deltaN_);


        // Face unit interface normal flux
        const surfaceVectorField& Sf = mesh.Sf();
        surfaceScalarField nHatf_ = nHatfv & Sf;

        volScalarField curvature
        (
         IOobject
         (
          "Curvature",
          runTime.timeName(),
          mesh,
          IOobject::NO_READ,
          IOobject::AUTO_WRITE
          ),

         -fvc::div(nHatf_)

         );
The thing that I can not understand is if I'm doing something wrong or if it is normal to find such values

thanks
andrea
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