threePhaseInterfaceProperties.C

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    Copyright (C) 2011-2017 OpenFOAM Foundation
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License
    This file is part of OpenFOAM.
 
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    for more details.
 
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#include "threePhaseInterfaceProperties.H"
#include "alphaContactAngleTwoPhaseFvPatchScalarField.H"
#include "mathematicalConstants.H"
#include "surfaceInterpolate.H"
#include "fvcDiv.H"
#include "fvcGrad.H"
#include "fvcSnGrad.H"
#include "unitConversion.H"
 
// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
void Foam::threePhaseInterfaceProperties::correctContactAngle
(
    surfaceVectorField::Boundary& nHatb
) const
{
    const volScalarField::Boundary& alpha1 =
        mixture_.alpha1().boundaryField();
    const volScalarField::Boundary& alpha2 =
        mixture_.alpha2().boundaryField();
    const volScalarField::Boundary& alpha3 =
        mixture_.alpha3().boundaryField();
    const volVectorField::Boundary& U =
        mixture_.U().boundaryField();
 
    const fvMesh& mesh = mixture_.U().mesh();
    const fvBoundaryMesh& boundary = mesh.boundary();
 
    forAll(boundary, patchi)
    {
        if (isA<alphaContactAngleTwoPhaseFvPatchScalarField>(alpha1[patchi]))
        {
            const alphaContactAngleTwoPhaseFvPatchScalarField& a2cap =
                refCast<const alphaContactAngleTwoPhaseFvPatchScalarField>
                (alpha2[patchi]);
 
            const alphaContactAngleTwoPhaseFvPatchScalarField& a3cap =
                refCast<const alphaContactAngleTwoPhaseFvPatchScalarField>
                (alpha3[patchi]);
 
            scalarField twoPhaseAlpha2(max(a2cap, scalar(0)));
            scalarField twoPhaseAlpha3(max(a3cap, scalar(0)));
 
            scalarField sumTwoPhaseAlpha
            (
                twoPhaseAlpha2 + twoPhaseAlpha3 + SMALL
            );
 
            twoPhaseAlpha2 /= sumTwoPhaseAlpha;
            twoPhaseAlpha3 /= sumTwoPhaseAlpha;
 
            fvsPatchVectorField& nHatp = nHatb[patchi];
 
            scalarField theta
            (
                degToRad()
              * (
                   twoPhaseAlpha2*(180 - a2cap.theta(U[patchi], nHatp))
                 + twoPhaseAlpha3*(180 - a3cap.theta(U[patchi], nHatp))
                )
            );
 
            vectorField nf(boundary[patchi].nf());
 
            // Reset nHatPatch to correspond to the contact angle
 
            scalarField a12(nHatp & nf);
 
            scalarField b1(cos(theta));
 
            scalarField b2(nHatp.size());
 
            forAll(b2, facei)
            {
                b2[facei] = cos(acos(a12[facei]) - theta[facei]);
            }
 
            scalarField det(1.0 - a12*a12);
 
            scalarField a((b1 - a12*b2)/det);
            scalarField b((b2 - a12*b1)/det);
 
            nHatp = a*nf + b*nHatp;
 
            nHatp /= (mag(nHatp) + deltaN_.value());
        }
    }
}
 
 
void Foam::threePhaseInterfaceProperties::calculateK()
{
    const volScalarField& alpha1 = mixture_.alpha1();
 
    const fvMesh& mesh = alpha1.mesh();
    const surfaceVectorField& Sf = mesh.Sf();
 
    // Cell gradient of alpha
    volVectorField gradAlpha(fvc::grad(alpha1));
 
    // Interpolated face-gradient of alpha
    surfaceVectorField gradAlphaf(fvc::interpolate(gradAlpha));
 
    // Face unit interface normal
    surfaceVectorField nHatfv(gradAlphaf/(mag(gradAlphaf) + deltaN_));
 
    correctContactAngle(nHatfv.boundaryFieldRef());
 
    // 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_);
    // nHat.boundaryFieldRef() = nHatfv.boundaryField();
    // K_ = -fvc::div(nHatf_) + (nHat & fvc::grad(nHatfv) & nHat);
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Foam::threePhaseInterfaceProperties::threePhaseInterfaceProperties
(
    const incompressibleThreePhaseMixture& mixture
)
:
    mixture_(mixture),
    cAlpha_
    (
        mixture.U().mesh().solverDict
        (
            mixture_.alpha1().name()
        ).get<scalar>("cAlpha")
    ),
    sigma12_("sigma12", dimMass/sqr(dimTime), mixture),
    sigma13_("sigma13", dimMass/sqr(dimTime), mixture),
 
    deltaN_
    (
        "deltaN",
        1e-8/cbrt(average(mixture.U().mesh().V()))
    ),
 
    nHatf_
    (
        IOobject
        (
            "nHatf",
            mixture.alpha1().time().timeName(),
            mixture.alpha1().mesh()
        ),
        mixture.alpha1().mesh(),
        dimensionedScalar(dimArea, Zero)
    ),
 
    K_
    (
        IOobject
        (
            "interfaceProperties:K",
            mixture.alpha1().time().timeName(),
            mixture.alpha1().mesh()
        ),
        mixture.alpha1().mesh(),
        dimensionedScalar(dimless/dimLength, Zero)
    )
{
    calculateK();
}
 
 
// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
Foam::tmp<Foam::surfaceScalarField>
Foam::threePhaseInterfaceProperties::surfaceTensionForce() const
{
    return fvc::interpolate(sigmaK())*fvc::snGrad(mixture_.alpha1());
}
 
 
Foam::tmp<Foam::volScalarField>
Foam::threePhaseInterfaceProperties::nearInterface() const
{
    return max
    (
        pos0(mixture_.alpha1() - 0.01)*pos0(0.99 - mixture_.alpha1()),
        pos0(mixture_.alpha2() - 0.01)*pos0(0.99 - mixture_.alpha2())
    );
}
 
 
// ************************************************************************* //