SprayParcel.C

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    Copyright (C) 2011-2017 OpenFOAM Foundation
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License
    This file is part of OpenFOAM.

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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

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#include "SprayParcel.H"
#include "BreakupModel.H"
#include "CompositionModel.H"
#include "AtomizationModel.H"

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

template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::setCellValues
(
    TrackCloudType& cloud,
    trackingData& td
)
{
    ParcelType::setCellValues(cloud, td);
}


template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::cellValueSourceCorrection
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalar dt
)
{
    ParcelType::cellValueSourceCorrection(cloud, td, dt);
}


template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::calc
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalar dt
)
{
    const auto& composition = cloud.composition();
    const auto& liquids = composition.liquids();

    // Check if parcel belongs to liquid core
    if (liquidCore() > 0.5)
    {
        // Liquid core parcels should not experience coupled forces
        cloud.forces().setCalcCoupled(false);
    }

    // Get old mixture composition
    scalarField X0(liquids.X(this->Y()));

    // Check if we have critical or boiling conditions
    scalar TMax = liquids.Tc(X0);
    const scalar T0 = this->T();
    const scalar pc0 = td.pc();
    if (liquids.pv(pc0, T0, X0) >= pc0*0.999)
    {
        // Set TMax to boiling temperature
        TMax = liquids.pvInvert(pc0, X0);
    }

    // Set the maximum temperature limit
    cloud.constProps().setTMax(TMax);

    // Store the parcel properties
    this->Cp() = liquids.Cp(pc0, T0, X0);
    sigma_ = liquids.sigma(pc0, T0, X0);
    const scalar rho0 = liquids.rho(pc0, T0, X0);
    this->rho() = rho0;
    const scalar mass0 = this->mass();
    mu_ = liquids.mu(pc0, T0, X0);

    ParcelType::calc(cloud, td, dt);

    if (td.keepParticle)
    {
        // Reduce the stripped parcel mass due to evaporation
        // assuming the number of particles remains unchanged
        this->ms() -= this->ms()*(mass0 - this->mass())/mass0;

        // Update Cp, sigma, density and diameter due to change in temperature
        // and/or composition
        scalar T1 = this->T();
        scalarField X1(liquids.X(this->Y()));

        this->Cp() = liquids.Cp(td.pc(), T1, X1);

        sigma_ = liquids.sigma(td.pc(), T1, X1);

        scalar rho1 = liquids.rho(td.pc(), T1, X1);
        this->rho() = rho1;

        mu_ = liquids.mu(td.pc(), T1, X1);

        scalar d1 = this->d()*cbrt(rho0/rho1);
        this->d() = d1;

        if (liquidCore() > 0.5)
        {
            calcAtomization(cloud, td, dt);

            // Preserve the total mass/volume by increasing the number of
            // particles in parcels due to breakup
            scalar d2 = this->d();
            this->nParticle() *= pow3(d1/d2);
        }
        else
        {
            calcBreakup(cloud, td, dt);
        }
    }

    // Restore coupled forces
    cloud.forces().setCalcCoupled(true);
}


template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::calcAtomization
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalar dt
)
{
    const auto& atomization = cloud.atomization();

    if (!atomization.active())
    {
        return;
    }

    const auto& composition = cloud.composition();
    const auto& liquids = composition.liquids();

    // Average molecular weight of carrier mix - assumes perfect gas
    scalar Wc = td.rhoc()*RR*td.Tc()/td.pc();
    scalar R = RR/Wc;
    scalar Tav = atomization.Taverage(this->T(), td.Tc());

    // Calculate average gas density based on average temperature
    scalar rhoAv = td.pc()/(R*Tav);

    scalar soi = cloud.injectors().timeStart();
    scalar currentTime = cloud.db().time().value();
    const vector pos(this->position());
    const vector& injectionPos = this->position0();

    // Disregard the continuous phase when calculating the relative velocity
    // (in line with the deactivated coupled assumption)
    scalar Urel = mag(this->U());

    scalar t0 = max(0.0, currentTime - this->age() - soi);
    scalar t1 = min(t0 + dt, cloud.injectors().timeEnd() - soi);

    // This should be the vol flow rate from when the parcel was injected
    scalar volFlowRate = cloud.injectors().volumeToInject(t0, t1)/dt;

    scalar chi = 0.0;
    if (atomization.calcChi())
    {
        chi = this->chi(cloud, td, liquids.X(this->Y()));
    }

    atomization.update
    (
        dt,
        this->d(),
        this->liquidCore(),
        this->tc(),
        this->rho(),
        mu_,
        sigma_,
        volFlowRate,
        rhoAv,
        Urel,
        pos,
        injectionPos,
        cloud.pAmbient(),
        chi,
        cloud.rndGen()
    );
}


template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::calcBreakup
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalar dt
)
{
    auto& breakup = cloud.breakup();

    if (!breakup.active())
    {
        return;
    }

    if (breakup.solveOscillationEq())
    {
        solveTABEq(cloud, td, dt);
    }

    // Average molecular weight of carrier mix - assumes perfect gas
    scalar Wc = td.rhoc()*RR*td.Tc()/td.pc();
    scalar R = RR/Wc;
    scalar Tav = cloud.atomization().Taverage(this->T(), td.Tc());

    // Calculate average gas density based on average temperature
    scalar rhoAv = td.pc()/(R*Tav);
    scalar muAv = td.muc();
    vector Urel = this->U() - td.Uc();
    scalar Urmag = mag(Urel);
    scalar Re = this->Re(rhoAv, this->U(), td.Uc(), this->d(), muAv);

    const typename TrackCloudType::parcelType& p =
        static_cast<const typename TrackCloudType::parcelType&>(*this);
    typename TrackCloudType::parcelType::trackingData& ttd =
        static_cast<typename TrackCloudType::parcelType::trackingData&>(td);
    const scalar mass = p.mass();
    const typename TrackCloudType::forceType& forces = cloud.forces();
    const forceSuSp Fcp = forces.calcCoupled(p, ttd, dt, mass, Re, muAv);
    const forceSuSp Fncp = forces.calcNonCoupled(p, ttd, dt, mass, Re, muAv);
    this->tMom() = mass/(Fcp.Sp() + Fncp.Sp() + ROOTVSMALL);

    const vector g = cloud.g().value();

    scalar parcelMassChild = 0.0;
    scalar dChild = 0.0;
    if
    (
        breakup.update
        (
            dt,
            g,
            this->d(),
            this->tc(),
            this->ms(),
            this->nParticle(),
            this->KHindex(),
            this->y(),
            this->yDot(),
            this->d0(),
            this->rho(),
            mu_,
            sigma_,
            this->U(),
            rhoAv,
            muAv,
            Urel,
            Urmag,
            this->tMom(),
            dChild,
            parcelMassChild
        )
    )
    {
        scalar Re = rhoAv*Urmag*dChild/muAv;

        // Add child parcel as copy of parent
        SprayParcel<ParcelType>* child = new SprayParcel<ParcelType>(*this);
        child->origId() = this->getNewParticleID();
        child->origProc() = Pstream::myProcNo();
        child->d() = dChild;
        child->d0() = dChild;
        const scalar massChild = child->mass();
        child->mass0() = massChild;
        child->nParticle() = parcelMassChild/massChild;

        const forceSuSp Fcp =
            forces.calcCoupled(*child, ttd, dt, massChild, Re, muAv);
        const forceSuSp Fncp =
            forces.calcNonCoupled(*child, ttd, dt, massChild, Re, muAv);

        child->age() = 0.0;
        child->liquidCore() = 0.0;
        child->KHindex() = 1.0;
        child->y() = cloud.breakup().y0();
        child->yDot() = cloud.breakup().yDot0();
        child->tc() = 0.0;
        child->ms() = -GREAT;
        child->injector() = this->injector();
        child->tMom() = massChild/(Fcp.Sp() + Fncp.Sp());
        child->user() = 0.0;
        child->calcDispersion(cloud, td, dt);

        cloud.addParticle(child);
    }
}


template<class ParcelType>
template<class TrackCloudType>
Foam::scalar Foam::SprayParcel<ParcelType>::chi
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalarField& X
) const
{
    // Modifications to take account of the flash boiling on primary break-up

    const auto& composition = cloud.composition();
    const auto& liquids = composition.liquids();

    scalar chi = 0.0;
    scalar T0 = this->T();
    scalar p0 = td.pc();
    scalar pAmb = cloud.pAmbient();

    scalar pv = liquids.pv(p0, T0, X);

    forAll(liquids, i)
    {
        if (pv >= 0.999*pAmb)
        {
            // Liquid is boiling - calc boiling temperature

            const liquidProperties& liq = liquids.properties()[i];
            scalar TBoil = liq.pvInvert(p0);

            scalar hl = liq.hl(pAmb, TBoil);
            scalar iTp = liq.h(pAmb, T0) - pAmb/liq.rho(pAmb, T0);
            scalar iTb = liq.h(pAmb, TBoil) - pAmb/liq.rho(pAmb, TBoil);

            chi += X[i]*(iTp - iTb)/hl;
        }
    }

    return clamp(chi, zero_one{});
}


template<class ParcelType>
template<class TrackCloudType>
void Foam::SprayParcel<ParcelType>::solveTABEq
(
    TrackCloudType& cloud,
    trackingData& td,
    const scalar dt
)
{
    const scalar& TABCmu = cloud.breakup().TABCmu();
    const scalar& TABtwoWeCrit = cloud.breakup().TABtwoWeCrit();
    const scalar& TABComega = cloud.breakup().TABComega();

    scalar r = 0.5*this->d();
    scalar r2 = r*r;
    scalar r3 = r*r2;

    // Inverse of characteristic viscous damping time
    scalar rtd = 0.5*TABCmu*mu_/(this->rho()*r2);

    // Oscillation frequency (squared)
    scalar omega2 = TABComega*sigma_/(this->rho()*r3) - rtd*rtd;

    if (omega2 > 0)
    {
        scalar omega = sqrt(omega2);
        scalar We =
            this->We(td.rhoc(), this->U(), td.Uc(), r, sigma_)/TABtwoWeCrit;

        // Initial values for y and yDot
        scalar y0 = this->y() - We;
        scalar yDot0 = this->yDot() + y0*rtd;

        // Update distortion parameters
        scalar c = cos(omega*dt);
        scalar s = sin(omega*dt);
        scalar e = exp(-rtd*dt);

        this->y() = We + e*(y0*c + (yDot0/omega)*s);
        this->yDot() = (We - this->y())*rtd + e*(yDot0*c - omega*y0*s);
    }
    else
    {
        // Reset distortion parameters
        this->y() = 0;
        this->yDot() = 0;
    }
}


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

template<class ParcelType>
Foam::SprayParcel<ParcelType>::SprayParcel(const SprayParcel<ParcelType>& p)
:
    ParcelType(p),
    d0_(p.d0_),
    position0_(p.position0_),
    sigma_(p.sigma_),
    mu_(p.mu_),
    liquidCore_(p.liquidCore_),
    KHindex_(p.KHindex_),
    y_(p.y_),
    yDot_(p.yDot_),
    tc_(p.tc_),
    ms_(p.ms_),
    injector_(p.injector_),
    tMom_(p.tMom_),
    user_(p.user_)
{}


template<class ParcelType>
Foam::SprayParcel<ParcelType>::SprayParcel
(
    const SprayParcel<ParcelType>& p,
    const polyMesh& mesh
)
:
    ParcelType(p, mesh),
    d0_(p.d0_),
    position0_(p.position0_),
    sigma_(p.sigma_),
    mu_(p.mu_),
    liquidCore_(p.liquidCore_),
    KHindex_(p.KHindex_),
    y_(p.y_),
    yDot_(p.yDot_),
    tc_(p.tc_),
    ms_(p.ms_),
    injector_(p.injector_),
    tMom_(p.tMom_),
    user_(p.user_)
{}


// * * * * * * * * * * * * * * IOStream operators  * * * * * * * * * * * * * //

#include "SprayParcelIO.C"


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