[Jasper Z]

Dear all, I am looking at the creatFields.H in MPPICInterFoam, a part of the codes are shown below:

volScalarField alphac
(
    IOobject
    (
        "alphac",
        runTime.timeName(),
        mesh,
        IOobject::READ_IF_PRESENT,
        IOobject::AUTO_WRITE
    ),
    mesh,
    dimensionedScalar(dimless, Zero),
    zeroGradientFvPatchScalarField::typeName
);
alphac.oldTime();

volScalarField alphacRho(alphac*rho);
alphacRho.oldTime();

Info<< "Constructing kinematicCloud " << endl;
basicKinematicMPPICCloud kinematicCloud
(
    "kinematicCloud",
    rho,
    U,
    mu,
    g
);

// Particle fraction upper limit
scalar alphacMin
(
    1.0
  - (
        kinematicCloud.particleProperties().subDict("constantProperties")
       .get<scalar>("alphaMax")
    )
);

// Update alphac from the particle locations
alphac = max(1.0 - kinematicCloud.theta(), alphacMin);
alphac.correctBoundaryConditions();

At the bottom of code, we can see that the updated alphac=1-theta, but I am wondering how to get the updated alpha1 and alpha2 from alphac? I don't know where the code is...

Thanks for your help,
Jasper

[Jasper Z]

After looking at the alphaEqn.H, alpha1 can be calculated via the following codes:

else
        {
            alphaPhi10 = talphaPhi1Un;

            MULES::explicitSolve
            (
                alphac,
                alpha1,
                phiCN,
                alphaPhi10,
                Sp,
                (Su + divU*min(alpha1(), scalar(1)))(),
                oneField(),
                zeroField()
            );
        }

        alpha2 = 1.0 - alpha1;

        mixture.correct();
    }

But why alpha2 = 1.0 - alpha1? shouldn't it be alphac-alpha1? Please give me a hint if anyone knows that