alphatJayatillekeWallFunctionFvPatchScalarField.C

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#include "alphatJayatillekeWallFunctionFvPatchScalarField.H"
#include "fluidThermophysicalTransportModel.H"
#include "addToRunTimeSelectionTable.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace compressible
{
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
scalar alphatJayatillekeWallFunctionFvPatchScalarField::maxExp_ = 50.0;
scalar alphatJayatillekeWallFunctionFvPatchScalarField::tolerance_ = 0.01;
label alphatJayatillekeWallFunctionFvPatchScalarField::maxIters_ = 10;
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
alphatJayatillekeWallFunctionFvPatchScalarField::
alphatJayatillekeWallFunctionFvPatchScalarField
(
    const fvPatch& p,
    const DimensionedField<scalar, volMesh>& iF,
    const dictionary& dict
)
:
    fixedValueFvPatchScalarField(p, iF, dict),
    Prt_(dict.lookupOrDefault<scalar>("Prt", 0.85))
{}
 
 
alphatJayatillekeWallFunctionFvPatchScalarField::
alphatJayatillekeWallFunctionFvPatchScalarField
(
    const alphatJayatillekeWallFunctionFvPatchScalarField& ptf,
    const fvPatch& p,
    const DimensionedField<scalar, volMesh>& iF,
    const fvPatchFieldMapper& mapper
)
:
    fixedValueFvPatchScalarField(ptf, p, iF, mapper),
    Prt_(ptf.Prt_)
{}
 
 
alphatJayatillekeWallFunctionFvPatchScalarField::
alphatJayatillekeWallFunctionFvPatchScalarField
(
    const alphatJayatillekeWallFunctionFvPatchScalarField& awfpsf,
    const DimensionedField<scalar, volMesh>& iF
)
:
    fixedValueFvPatchScalarField(awfpsf, iF),
    Prt_(awfpsf.Prt_)
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
tmp<scalarField> alphatJayatillekeWallFunctionFvPatchScalarField::P
(
    const scalarField& Prat
)
{
    return 9.24*(pow(Prat, 0.75) - 1.0)*(1.0 + 0.28*exp(-0.007*Prat));
}
 
 
tmp<scalarField> alphatJayatillekeWallFunctionFvPatchScalarField::yPlusTherm
(
    const nutWallFunctionFvPatchScalarField& nutw,
    const scalarField& P,
    const scalarField& Prat
)
{
    tmp<scalarField> typt(new scalarField(nutw.size()));
    scalarField& ypt = typt.ref();
 
    const scalar E = nutw.E();
    const scalar kappa = nutw.kappa();
 
    forAll(ypt, facei)
    {
        ypt[facei] = 11.0;
 
        for (int i=0; i<maxIters_; i++)
        {
            const scalar f =
                ypt[facei] - (log(E*ypt[facei])/kappa + P[facei])/Prat[facei];
 
            const scalar df = 1.0 - 1.0/(ypt[facei]*nutw.kappa()*Prat[facei]);
 
            const scalar dypt = - f/df;
 
            ypt[facei] += dypt;
 
            if (ypt[facei] < vSmall)
            {
                ypt[facei] = 0;
                break;
            }
 
            if (mag(dypt) < tolerance_)
            {
                break;
            }
        }
    }
 
    return typt;
}
 
 
tmp<scalarField> alphatJayatillekeWallFunctionFvPatchScalarField::alphat
(
    const fluidThermophysicalTransportModel& ttm,
    const scalar Prt,
    const label patchi
)
{
    const compressibleMomentumTransportModel& turbModel =
        ttm.momentumTransport();
 
    const nutWallFunctionFvPatchScalarField& nutw =
        nutWallFunctionFvPatchScalarField::nutw(turbModel, patchi);
 
    const scalar Cmu25 = pow025(nutw.Cmu());
 
    const scalarField& y = turbModel.y()[patchi];
 
    const tmp<scalarField> tnuw = turbModel.nu(patchi);
    const scalarField& nuw = tnuw();
 
    const tmp<scalarField> talphaw
    (
        ttm.thermo().kappa().boundaryField()[patchi]
       /ttm.thermo().Cp().boundaryField()[patchi]
    );
    const scalarField& alphaw = talphaw();
 
    const tmp<volScalarField> tk = turbModel.k();
    const volScalarField& k = tk();
 
    const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
    const scalarField magUp(mag(Uw.patchInternalField() - Uw));
    const scalarField magGradUw(mag(Uw.snGrad()));
 
    const scalarField& rhow = turbModel.rho().boundaryField()[patchi];
    const fvPatchScalarField& hew = ttm.thermo().he().boundaryField()[patchi];
 
    // Enthalpy gradient
    const scalarField gradHew(hew.snGrad());
 
    // Molecular Prandtl number
    const scalarField Pr(rhow*nuw/alphaw);
 
    // Molecular-to-turbulent Prandtl number ratio
    const scalarField Prat(Pr/Prt);
 
    // Thermal sublayer thickness
    const scalarField P
    (
        alphatJayatillekeWallFunctionFvPatchScalarField::P(Prat)
    );
    const scalarField yPlusTherm
    (
        alphatJayatillekeWallFunctionFvPatchScalarField::yPlusTherm
        (
            nutw,
            P,
            Prat
        )
    );
 
    // Populate boundary values
    tmp<scalarField> talphatw(new scalarField(nutw.size()));
    scalarField& alphatw = talphatw.ref();
    forAll(alphatw, facei)
    {
        const label celli = nutw.patch().faceCells()[facei];
 
        const scalar uTau = Cmu25*sqrt(k[celli]);
 
        const scalar yPlus = uTau*y[facei]/nuw[facei];
 
        // Evaluate new effective thermal diffusivity
        scalar alphaEff = 0.0;
        if (yPlus < yPlusTherm[facei])
        {
            const scalar A = gradHew[facei]*rhow[facei]*uTau*y[facei];
 
            const scalar B = gradHew[facei]*Pr[facei]*yPlus;
 
            const scalar C = Pr[facei]*0.5*rhow[facei]*uTau*sqr(magUp[facei]);
 
            alphaEff = (A - C)/(B + sign(B)*rootVSmall);
        }
        else
        {
            const scalar A = gradHew[facei]*rhow[facei]*uTau*y[facei];
 
            const scalar B =
                gradHew[facei]*Prt
               *(1.0/nutw.kappa()*log(nutw.E()*yPlus) + P[facei]);
 
            const scalar magUc =
                uTau/nutw.kappa()
               *log(nutw.E()*yPlusTherm[facei]) - mag(Uw[facei]);
 
            const scalar C =
                0.5*rhow[facei]*uTau
               *(Prt*sqr(magUp[facei]) + (Pr[facei] - Prt)*sqr(magUc));
 
            alphaEff = (A - C)/(B + sign(B)*rootVSmall);
        }
 
        // Bounds on turbulent thermal diffusivity
        static const scalar alphatwMin = 0;
        const scalar alphatwMax = great*alphaw[facei]*nutw[facei]/nuw[facei];
 
        // Update turbulent thermal diffusivity
        alphatw[facei] =
            min(max(alphaEff - alphaw[facei], alphatwMin), alphatwMax);
    }
 
    return talphatw;
}
 
 
void alphatJayatillekeWallFunctionFvPatchScalarField::updateCoeffs()
{
    if (updated())
    {
        return;
    }
 
    const fluidThermophysicalTransportModel& ttm =
        db().lookupType<fluidThermophysicalTransportModel>
        (
            internalField().group()
        );
 
    this->operator==(alphat(ttm, Prt_, patch().index()));
 
    fixedValueFvPatchField<scalar>::updateCoeffs();
}
 
 
void alphatJayatillekeWallFunctionFvPatchScalarField::write(Ostream& os) const
{
    fvPatchField<scalar>::write(os);
    writeEntry(os, "Prt", Prt_);
    writeEntry(os, "value", *this);
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
makePatchTypeField
(
    fvPatchScalarField,
    alphatJayatillekeWallFunctionFvPatchScalarField
);
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace compressible
} // End namespace Foam
 
// ************************************************************************* //