[Amadeus]

Hello everyone!

I am studying the source code of the interFoam solver in OpenFOAM. When calculating surface tension, interFoam needs to compute the interface curvature. My question is about the calculateK() function and the correctContactAngle() function in the interfaceProperties.C file. These functions do not seem to consider the case where the interface normal vector and the boundary normal vector are collinear. How is the curvature calculated in such cases?

Additionally, after calculating the curvature at the boundary, how can the curvature of other interface cells be corrected to ensure that the interface curvature is consistent?

void Foam::interfaceProperties::calculateK()
{
    const fvMesh& mesh = alpha1_.mesh();
    const surfaceVectorField& Sf = mesh.Sf();

    // Cell gradient of alpha
    const volVectorField gradAlpha(fvc::grad(alpha1_, "nHat"));

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

    //gradAlphaf -=
    //    (mesh.Sf()/mesh.magSf())
    //   *(fvc::snGrad(alpha1_) - (mesh.Sf() & gradAlphaf)/mesh.magSf());

    // Face unit interface normal
    surfaceVectorField nHatfv(gradAlphaf/(mag(gradAlphaf) + deltaN_));
    // surfaceVectorField nHatfv
    // (
    //     (gradAlphaf + deltaN_*vector(0, 0, 1)
    //    *sign(gradAlphaf.component(vector::Z)))/(mag(gradAlphaf) + deltaN_)
    // );
    correctContactAngle(nHatfv.boundaryFieldRef(), gradAlphaf.boundaryField());

    // Face unit interface normal flux
    nHatf_ = nHatfv & Sf;

    // Simple expression for curvature
    K_ = -fvc::div(nHatf_);

    // Complex expression for curvature.
    // Correction is formally zero but numerically non-zero.
    /*
    volVectorField nHat(gradAlpha/(mag(gradAlpha) + deltaN_));
    forAll(nHat.boundaryField(), patchi)
    {
        nHat.boundaryFieldRef()[patchi] = nHatfv.boundaryField()[patchi];
    }

    K_ = -fvc::div(nHatf_) + (nHat & fvc::grad(nHatfv) & nHat);
    */
}

I noticed that some code in the calculateK() function is commented out. In the commented code, it appears that OpenFOAM handles these situations. Why did OpenFOAM comment out this code?