LISA.C

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#include <OpenFOAM/error.H>

#include "LISA.H"
#include <OpenFOAM/addToRunTimeSelectionTable.H>
#include <reactionThermophysicalModels/basicMultiComponentMixture.H>

#include <pdf/RosinRammler.H>

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

namespace Foam
{

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

defineTypeNameAndDebug(LISA, 0);

addToRunTimeSelectionTable
(
    atomizationModel,
    LISA,
    dictionary
);

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

// Construct from components
LISA::LISA
(
    const dictionary& dict,
    spray& sm
)
:
    atomizationModel(dict, sm),
    coeffsDict_(dict.subDict(typeName+"Coeffs")),
    rndGen_(sm.rndGen()),
    Cl_(readScalar(coeffsDict_.lookup("Cl"))),
    cTau_(readScalar(coeffsDict_.lookup("cTau"))),
    Q_(readScalar(coeffsDict_.lookup("Q"))),
    J_(readScalar(coeffsDict_.lookup("J")))
{}


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

LISA::~LISA()
{}


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

void LISA::atomizeParcel
(
    parcel& p,
    const scalar deltaT,
    const vector& vel,
    const liquidMixture& fuels
) const
{


    const PtrList<volScalarField>& Y = spray_.composition().Y();

    label Ns = Y.size();
    label cellI = p.cell();
    scalar pressure = spray_.p()[cellI];
    scalar temperature = spray_.T()[cellI];
    scalar Taverage = p.T() + (temperature - p.T())/3.0;
    scalar Winv = 0.0;

    for(label i=0; i<Ns; i++)
    {
        Winv += Y[i][cellI]/spray_.gasProperties()[i].W();
    }

    scalar R = specie::RR*Winv;

    // ideal gas law to evaluate density
    scalar rhoAverage = pressure/R/Taverage;
    //scalar nuAverage = muAverage/rhoAverage;
    scalar sigma = fuels.sigma(pressure, p.T(), p.X());

    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
    //     The We and Re numbers are to be evaluated using the 1/3 rule.
    // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

    scalar WeberNumber = p.We(vel, rhoAverage, sigma);

    scalar tau = 0.0;
    scalar dL = 0.0;
    scalar k = 0.0;
    scalar muFuel = fuels.mu(pressure, p.T(), p.X());
    scalar rhoFuel = fuels.rho(1.0e+5, p.T(), p.X());
    scalar nuFuel = muFuel/rhoFuel;

    vector uDir = p.U()/mag(p.U());

    scalar uGas = mag(vel & uDir);
    vector Ug = uGas*uDir;

/*
    TL
    It might be the relative velocity between Liquid and Gas, but I use the
    absolute velocity of the parcel as suggested by the authors
*/

//    scalar U = mag(p.Urel(vel));
    scalar U = mag(p.U());

    p.ct() += deltaT;

    scalar Q = rhoAverage/rhoFuel;

    const injectorType& it =
        spray_.injectors()[label(p.injector())].properties();

    if (it.nHoles() > 1)
    {
        Info << "Warning: This atomization model is not suitable for multihole injector." << endl
             << "Only the first hole will be used." << endl;
    }

    const vector itPosition = it.position(0);
    scalar pWalk = mag(p.position() - itPosition);

//  Updating liquid sheet tickness... that is the droplet diameter

    const vector direction = it.direction(0, spray_.runTime().value());

    scalar h = (p.position() - itPosition) & direction;

    scalar d = sqrt(sqr(pWalk)-sqr(h));

    scalar time = pWalk/mag(p.U());

    scalar elapsedTime = spray_.runTime().value();

    scalar massFlow = it.massFlowRate(max(0.0,elapsedTime-time));

    scalar hSheet = massFlow/(mathematicalConstant::pi*d*rhoFuel*mag(p.U()));

    p.d() = min(hSheet,p.d());

    if(WeberNumber > 27.0/16.0)
    {

        scalar kPos = 0.0;
        scalar kNeg = Q*pow(U, 2.0)*rhoFuel/sigma;

        scalar derivativePos = sqrt
        (
            Q*pow(U,2.0)
        );

        scalar derivativeNeg =
        (
            8.0*pow(nuFuel, 2.0)*pow(kNeg, 3.0)
            + Q*pow(U, 2.0)*kNeg
            - 3.0*sigma/2.0/rhoFuel*pow(kNeg, 2.0)
        )
        /
        sqrt
        (
            4.0*pow(nuFuel, 2.0)*pow(kNeg, 4.0)
            + Q*pow(U, 2.0)*pow(kNeg, 2.0)
            - sigma*pow(kNeg, 3.0)/rhoFuel
        )
        -
        4.0*nuFuel*kNeg;

        scalar kOld = 0.0;


        for(label i=0; i<40; i++)
        {

            k = kPos - (derivativePos/((derivativeNeg-derivativePos)/(kNeg-kPos)));

            scalar derivativek =
            (
                8.0*pow(nuFuel, 2.0)*pow(k, 3.0)
                + Q*pow(U, 2.0)*k
                - 3.0*sigma/2.0/rhoFuel*pow(k, 2.0)
            )
            /
            sqrt
            (
                4.0*pow(nuFuel, 2.0)*pow(k, 4.0)
                + Q*pow(U, 2.0)*pow(k, 2.0)
                - sigma*pow(k, 3.0)/rhoFuel
            )
            -
            4.0*nuFuel*k;

            if(derivativek > 0)
            {
                derivativePos = derivativek;
                kPos = k;
            }
            else
            {
                derivativeNeg = derivativek;
                kNeg = k;
            }

            if(mag(k-kOld)/k < 1e-4)
            {
                break;
            }

            kOld = k;

        }

        scalar omegaS =
        - 2.0 * nuFuel * pow(k, 2.0)
        + sqrt
        (
                4.0*pow(nuFuel, 2.0)*pow(k, 4.0)
            +   Q*pow(U, 2.0)*pow(k, 2.0)
            -   sigma*pow(k, 3.0)/rhoFuel
        );

        tau = cTau_/omegaS;

        dL = sqrt(8.0*p.d()/k);

    }
    else
    {

        k =
        rhoAverage*pow(U, 2.0)
        /
        2.0*sigma;

        scalar J = pWalk*p.d()/2.0;

        tau = pow(3.0*cTau_,2.0/3.0)*cbrt(J*sigma/(sqr(Q)*pow(U,4.0)*rhoFuel));

        dL = sqrt(4.0*p.d()/k);
    }



    scalar kL =
        1.0
        /
        (
            dL *
            pow(0.5 + 1.5 * muFuel/pow((rhoFuel*sigma*dL), 0.5), 0.5)
        );

    scalar dD = cbrt(3.0*mathematicalConstant::pi*pow(dL, 2.0)/kL);

    scalar lisaExp = 0.27;
    scalar ambientPressure = 1.0e+5;

    scalar pRatio = spray_.ambientPressure()/ambientPressure;

    dD = dD*pow(pRatio,lisaExp);

//  modifications to take account of the flash boiling on primary breakUp

    scalar pExp = 0.135;

    scalar chi = 0.0;

    label Nf = fuels.components().size();

    scalar Td = p.T();

    for(label i = 0; i < Nf ; i++)
    {

        if(fuels.properties()[i].pv(spray_.ambientPressure(), Td) >= 0.999*spray_.ambientPressure())
        {

//          The fuel is boiling.....
//          Calculation of the boiling temperature

            scalar tBoilingSurface = Td;

            label Niter = 200;

            for(label k=0; k< Niter ; k++)
            {
                scalar pBoil = fuels.properties()[i].pv(pressure, tBoilingSurface);

                if(pBoil > pressure)
                {
                    tBoilingSurface = tBoilingSurface - (Td-temperature)/Niter;
                }
                else
                {
                    break;
                }
            }

            scalar hl = fuels.properties()[i].hl(spray_.ambientPressure(), tBoilingSurface);
            scalar iTp = fuels.properties()[i].h(spray_.ambientPressure(), Td) - spray_.ambientPressure()/fuels.properties()[i].rho(spray_.ambientPressure(), Td);
            scalar iTb = fuels.properties()[i].h(spray_.ambientPressure(), tBoilingSurface) - spray_.ambientPressure()/fuels.properties()[i].rho(spray_.ambientPressure(), tBoilingSurface);

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

        }
    }

    //  bounding chi

    chi = max(chi, 0.0);
    chi = min(chi, 1.0);

    //  modifing dD to take account of flash boiling

    dD = dD*(1.0 - chi*pow(pRatio, -pExp));

    scalar lBU = Cl_ * mag(p.U())*tau;

    if(pWalk > lBU)
    {

        p.liquidCore() = 0.0;

//      calculate the new diameter with a Rosin Rammler distribution

        scalar minValue = min(p.d(),dD/10.0);

        scalar maxValue = dD;

        if(maxValue - minValue < SMALL)
        {
            minValue = p.d()/10.0;
        }

        scalar range = maxValue - minValue;

        scalar y = 0;
        scalar x = 0;

        bool success = false;

        while(!success)
        {

            x = minValue + range*rndGen_.scalar01();
            y = rndGen_.scalar01();

            scalar p = 0.0;

            scalar nExp = 1;

            scalar xx = pow(x/dD, nExp);

            p = xx*exp(-xx);

            if (y<p)
            {
                success = true;
            }

        }

//  New droplet diameter

        p.d() = x;
        p.ct() = 0.0;

    }


}


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

} // End namespace Foam

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