COxidationMurphyShaddix.C

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#include "COxidationMurphyShaddix.H"
#include "mathematicalConstants.H"

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

template<class CloudType>
Foam::label Foam::COxidationMurphyShaddix<CloudType>::maxIters_ = 1000;

template<class CloudType>
Foam::scalar Foam::COxidationMurphyShaddix<CloudType>::tolerance_ = 1e-06;


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

template<class CloudType>
Foam::COxidationMurphyShaddix<CloudType>::COxidationMurphyShaddix
(
    const dictionary& dict,
    CloudType& owner
)
:
    SurfaceReactionModel<CloudType>(dict, owner, typeName),
    D0_(readScalar(this->coeffDict().lookup("D0"))),
    rho0_(readScalar(this->coeffDict().lookup("rho0"))),
    T0_(readScalar(this->coeffDict().lookup("T0"))),
    Dn_(readScalar(this->coeffDict().lookup("Dn"))),
    A_(readScalar(this->coeffDict().lookup("A"))),
    E_(readScalar(this->coeffDict().lookup("E"))),
    n_(readScalar(this->coeffDict().lookup("n"))),
    WVol_(readScalar(this->coeffDict().lookup("WVol"))),
    CsLocalId_(-1),
    O2GlobalId_(owner.composition().carrierId("O2")),
    CO2GlobalId_(owner.composition().carrierId("CO2")),
    WC_(0.0),
    WO2_(0.0),
    HcCO2_(0.0)
{
    // Determine Cs ids
    label idSolid = owner.composition().idSolid();
    CsLocalId_ = owner.composition().localId(idSolid, "C");

    // Set local copies of thermo properties
    WO2_ = owner.thermo().carrier().W(O2GlobalId_);
    const scalar WCO2 = owner.thermo().carrier().W(CO2GlobalId_);
    WC_ = WCO2 - WO2_;

    HcCO2_ = owner.thermo().carrier().Hc(CO2GlobalId_);

    const scalar YCloc = owner.composition().Y0(idSolid)[CsLocalId_];
    const scalar YSolidTot = owner.composition().YMixture0()[idSolid];
    Info<< "    C(s): particle mass fraction = " << YCloc*YSolidTot << endl;
}


template<class CloudType>
Foam::COxidationMurphyShaddix<CloudType>::COxidationMurphyShaddix
(
    const COxidationMurphyShaddix<CloudType>& srm
)
:
    SurfaceReactionModel<CloudType>(srm),
    D0_(srm.D0_),
    rho0_(srm.rho0_),
    T0_(srm.T0_),
    Dn_(srm.Dn_),
    A_(srm.A_),
    E_(srm.E_),
    n_(srm.n_),
    WVol_(srm.WVol_),
    CsLocalId_(srm.CsLocalId_),
    O2GlobalId_(srm.O2GlobalId_),
    CO2GlobalId_(srm.CO2GlobalId_),
    WC_(srm.WC_),
    WO2_(srm.WO2_),
    HcCO2_(srm.HcCO2_)
{}


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

template<class CloudType>
Foam::COxidationMurphyShaddix<CloudType>::~COxidationMurphyShaddix()
{}


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

template<class CloudType>
Foam::scalar Foam::COxidationMurphyShaddix<CloudType>::calculate
(
    const scalar dt,
    const label celli,
    const scalar d,
    const scalar T,
    const scalar Tc,
    const scalar pc,
    const scalar rhoc,
    const scalar mass,
    const scalarField& YGas,
    const scalarField& YLiquid,
    const scalarField& YSolid,
    const scalarField& YMixture,
    const scalar N,
    scalarField& dMassGas,
    scalarField& dMassLiquid,
    scalarField& dMassSolid,
    scalarField& dMassSRCarrier
) const
{
    // Fraction of remaining combustible material
    const label idSolid = CloudType::parcelType::SLD;
    const scalar fComb = YMixture[idSolid]*YSolid[CsLocalId_];

    // Surface combustion until combustible fraction is consumed
    if (fComb < small)
    {
        return 0.0;
    }

    const SLGThermo& thermo = this->owner().thermo();

    // Cell carrier phase O2 species density [kg/m^3]
    const scalar rhoO2 = rhoc*thermo.carrier().Y(O2GlobalId_)[celli];

    if (rhoO2 < small)
    {
        return 0.0;
    }

    // Particle surface area [m^2]
    const scalar Ap = constant::mathematical::pi*sqr(d);

    // Calculate diffision constant at continuous phase temperature
    // and density [m^2/s]
    const scalar D = D0_*(rho0_/rhoc)*pow(Tc/T0_, Dn_);

    // Far field partial pressure O2 [Pa]
    const scalar ppO2 = rhoO2/WO2_*RR*Tc;

    // Total molar concentration of the carrier phase [kmol/m^3]
    const scalar C = pc/(RR*Tc);

    if (debug)
    {
        Pout<< "mass  = " << mass << nl
            << "fComb = " << fComb << nl
            << "Ap    = " << Ap << nl
            << "dt    = " << dt << nl
            << "C     = " << C << nl
            << endl;
    }

    // Molar reaction rate per unit surface area [kmol/(m^2.s)]
    scalar qCsOld = 0;
    scalar qCs = 1;

    const scalar qCsLim = mass*fComb/(WC_*Ap*dt);

    if (debug)
    {
        Pout<< "qCsLim = " << qCsLim << endl;
    }

    label iter = 0;
    while ((mag(qCs - qCsOld)/qCs > tolerance_) && (iter <= maxIters_))
    {
        qCsOld = qCs;
        const scalar PO2Surface = ppO2*exp(-(qCs + N)*d/(2*C*D));
        qCs = A_*exp(-E_/(RR*T))*pow(PO2Surface, n_);
        qCs = (100.0*qCs + iter*qCsOld)/(100.0 + iter);
        qCs = min(qCs, qCsLim);

        if (debug)
        {
            Pout<< "iter = " << iter
                << ", qCsOld = " << qCsOld
                << ", qCs = " << qCs
                << nl << endl;
        }

        iter++;
    }

    if (iter > maxIters_)
    {
        WarningInFunction
            << "iter limit reached (" << maxIters_ << ")" << nl << endl;
    }

    // Calculate the number of molar units reacted
    scalar dOmega = qCs*Ap*dt;

    // Add to carrier phase mass transfer
    dMassSRCarrier[O2GlobalId_] += -dOmega*WO2_;
    dMassSRCarrier[CO2GlobalId_] += dOmega*(WC_ + WO2_);

    // Add to particle mass transfer
    dMassSolid[CsLocalId_] += dOmega*WC_;

    const scalar HsC = thermo.solids().properties()[CsLocalId_].Hs(T);

    // carrier sensible enthalpy exchange handled via change in mass

    // Heat of reaction [J]
    return dOmega*(WC_*HsC - (WC_ + WO2_)*HcCO2_);
}


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