standardPhaseChange.C

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    Copyright (C) 2020 OpenCFD Ltd.
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#include "standardPhaseChange.H"
#include "addToRunTimeSelectionTable.H"
#include "thermoSingleLayer.H"
#include "zeroField.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
(
    surfaceFilmRegionModel& film,
    const dictionary& dict
)
:
    phaseChangeModel(typeName, film, dict),
    deltaMin_(coeffDict_.get<scalar>("deltaMin")),
    L_(coeffDict_.get<scalar>("L")),
    TbFactor_(coeffDict_.getOrDefault<scalar>("TbFactor", 1.1)),
    YInfZero_(coeffDict_.getOrDefault<Switch>("YInfZero", false))
{}
 
 
// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
template<class YInfType>
void standardPhaseChange::correctModel
(
    const scalar dt,
    scalarField& availableMass,
    scalarField& dMass,
    scalarField& dEnergy,
    YInfType YInf
)
{
    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& pInf = film.pPrimary();
    const scalarField& T = film.T();
    const scalarField& hs = film.hs();
    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), availableMass - deltaMin_*rho*magSf)
    );
 
    // Molecular weight of vapour [kg/kmol]
    const scalar Wvap = thermo.carrier().W(vapId);
 
    // Molecular weight of liquid [kg/kmol]
    const scalar Wliq = filmThermo.W();
 
    forAll(dMass, celli)
    {
        scalar dm = 0;
 
        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);
                dm = 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;
 
                // 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
                dm = dt*magSf[celli]*rhoInfc*hm*(Ys - YInf[celli])/(1.0 - Ys);
            }
 
            dMass[celli] += min(limMass[celli], max(dm, 0));
 
            // Heat is assumed to be removed by heat-transfer to the wall
            // so the energy remains unchanged by the phase-change.
            dEnergy[celli] += dm*hs[celli];
            // dEnergy[celli] += dm*(hs[celli] + hVap);
        }
    }
}
 
 
void standardPhaseChange::correctModel
(
    const scalar dt,
    scalarField& availableMass,
    scalarField& dMass,
    scalarField& dEnergy
)
{
    if (YInfZero_)
    {
        correctModel(dt, availableMass, dMass, dEnergy, zeroField());
    }
    else
    {
        const thermoSingleLayer& film = filmType<thermoSingleLayer>();
        const label vapId = film.thermo().carrierId(film.filmThermo().name());
        const scalarField& YInf = film.YPrimary()[vapId];
 
        correctModel(dt, availableMass, dMass, dEnergy, YInf);
    }
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace surfaceFilmModels
} // End namespace regionModels
} // End namespace Foam
 
// ************************************************************************* //