standardPhaseChange.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
     \\/     M anipulation  |
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License
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#include "standardPhaseChange.H"
#include "addToRunTimeSelectionTable.H"
#include "thermoSingleLayer.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{
namespace regionModels
{
namespace surfaceFilmModels
{

// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //

defineTypeNameAndDebug(standardPhaseChange, 0);

addToRunTimeSelectionTable
(
    phaseChangeModel,
    standardPhaseChange,
    dictionary
);

// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //

scalar standardPhaseChange::Sh
(
    const scalar Re,
    const scalar Sc
) const
{
    if (Re < 5.0E+05)
    {
        return 0.664*sqrt(Re)*cbrt(Sc);
    }
    else
    {
        return 0.037*pow(Re, 0.8)*cbrt(Sc);
    }
}


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

standardPhaseChange::standardPhaseChange
(
    surfaceFilmModel& owner,
    const dictionary& dict
)
:
    phaseChangeModel(typeName, owner, dict),
    deltaMin_(readScalar(coeffDict_.lookup("deltaMin"))),
    L_(readScalar(coeffDict_.lookup("L"))),
    TbFactor_(coeffDict_.lookupOrDefault<scalar>("TbFactor", 1.1))
{}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

standardPhaseChange::~standardPhaseChange()
{}


// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //

void standardPhaseChange::correctModel
(
    const scalar dt,
    scalarField& availableMass,
    scalarField& dMass,
    scalarField& dEnergy
)
{
    const thermoSingleLayer& film = filmType<thermoSingleLayer>();

    // set local thermo properties
    const SLGThermo& thermo = film.thermo();
    const filmThermoModel& filmThermo = film.filmThermo();
    const label vapId = thermo.carrierId(filmThermo.name());

    // retrieve fields from film model
    const scalarField& delta = film.delta();
    const scalarField& YInf = film.YPrimary()[vapId];
    const scalarField& pInf = film.pPrimary();
    const scalarField& T = film.T();
    const scalarField& rho = film.rho();
    const scalarField& rhoInf = film.rhoPrimary();
    const scalarField& muInf = film.muPrimary();
    const scalarField& magSf = film.magSf();
    const vectorField dU(film.UPrimary() - film.Us());
    const scalarField limMass
    (
        max(scalar(0.0), availableMass - deltaMin_*rho*magSf)
    );

    forAll(dMass, celli)
    {
        if (delta[celli] > deltaMin_)
        {
            // cell pressure [Pa]
            const scalar pc = pInf[celli];

            // calculate the boiling temperature
            const scalar Tb = filmThermo.Tb(pc);

            // local temperature - impose lower limit of 200 K for stability
            const scalar Tloc = min(TbFactor_*Tb, max(200.0, T[celli]));

            // saturation pressure [Pa]
            const scalar pSat = filmThermo.pv(pc, Tloc);

            // latent heat [J/kg]
            const scalar hVap = filmThermo.hl(pc, Tloc);

            // calculate mass transfer
            if (pSat >= 0.95*pc)
            {
                // boiling
                const scalar Cp = filmThermo.Cp(pc, Tloc);
                const scalar Tcorr = max(0.0, T[celli] - Tb);
                const scalar qCorr = limMass[celli]*Cp*(Tcorr);
                dMass[celli] = qCorr/hVap;
            }
            else
            {
                // Primary region density [kg/m3]
                const scalar rhoInfc = rhoInf[celli];

                // Primary region viscosity [Pa.s]
                const scalar muInfc = muInf[celli];

                // Reynolds number
                const scalar Re = rhoInfc*mag(dU[celli])*L_/muInfc;

                // molecular weight of vapour [kg/kmol]
                const scalar Wvap = thermo.carrier().W(vapId);

                // molecular weight of liquid [kg/kmol]
                const scalar Wliq = filmThermo.W();

                // vapour mass fraction at interface
                const scalar Ys = Wliq*pSat/(Wliq*pSat + Wvap*(pc - pSat));

                // vapour diffusivity [m2/s]
                const scalar Dab = filmThermo.D(pc, Tloc);

                // Schmidt number
                const scalar Sc = muInfc/(rhoInfc*(Dab + ROOTVSMALL));

                // Sherwood number
                const scalar Sh = this->Sh(Re, Sc);

                // mass transfer coefficient [m/s]
                const scalar hm = Sh*Dab/(L_ + ROOTVSMALL);

                // add mass contribution to source
                dMass[celli] =
                    dt*magSf[celli]*rhoInfc*hm*(Ys - YInf[celli])/(1.0 - Ys);
            }

            dMass[celli] = min(limMass[celli], max(0.0, dMass[celli]));
            dEnergy[celli] = dMass[celli]*hVap;
        }
    }
}


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace surfaceFilmModels
} // End namespace regionModels
} // End namespace Foam

// ************************************************************************* //