PilchErdman.C

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    Copyright (C) 2011-2013 OpenFOAM Foundation
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License
    This file is part of OpenFOAM.
 
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    for more details.
 
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#include "PilchErdman.H"
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
template<class CloudType>
Foam::PilchErdman<CloudType>::PilchErdman
(
    const dictionary& dict,
    CloudType& owner
)
:
    BreakupModel<CloudType>(dict, owner, typeName),
    B1_(0.375),
    B2_(0.2274)
{
    if (!this->defaultCoeffs(true))
    {
        this->coeffDict().readEntry("B1", B1_);
        this->coeffDict().readEntry("B2", B2_);
    }
}
 
 
template<class CloudType>
Foam::PilchErdman<CloudType>::PilchErdman(const PilchErdman<CloudType>& bum)
:
    BreakupModel<CloudType>(bum),
    B1_(bum.B1_),
    B2_(bum.B2_)
{}
 
 
// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
template<class CloudType>
Foam::PilchErdman<CloudType>::~PilchErdman()
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
template<class CloudType>
bool Foam::PilchErdman<CloudType>::update
(
    const scalar dt,
    const vector& g,
    scalar& d,
    scalar& tc,
    scalar& ms,
    scalar& nParticle,
    scalar& KHindex,
    scalar& y,
    scalar& yDot,
    const scalar d0,
    const scalar rho,
    const scalar mu,
    const scalar sigma,
    const vector& U,
    const scalar rhoc,
    const scalar muc,
    const vector& Urel,
    const scalar Urmag,
    const scalar tMom,
    scalar& dChild,
    scalar& massChild
)
{
    // Weber number - eq (1)
    scalar We = rhoc*sqr(Urmag)*d/sigma;
 
    // Ohnesorge number - eq (2)
    scalar Oh = mu/sqrt(rho*d*sigma);
 
    // Critical Weber number - eq (5)
    scalar Wec = 12.0*(1.0 + 1.077*pow(Oh, 1.6));
 
    if (We > Wec)
    {
        // We > 2670, wave crest stripping - eq (12)
        scalar taubBar = 5.5;
 
        if (We < 2670)
        {
            if (We > 351)
            {
                // sheet stripping - eq (11)
                taubBar = 0.766*pow(We - 12.0, 0.25);
            }
            else if (We > 45)
            {
                // bag-and-stamen breakup  - eq (10)
                taubBar = 14.1*pow(We - 12.0, 0.25);
            }
            else if (We > 18)
            {
                // bag breakup - eq (9)
                taubBar = 2.45*pow(We - 12.0, 0.25);
            }
            else if (We > 12)
            {
                // vibrational breakup - eq (8)
                taubBar = 6.0*pow(We - 12.0, -0.25);
            }
            else
            {
                // no break-up
                taubBar = GREAT;
            }
        }
 
        scalar rho12 = sqrt(rhoc/rho);
 
        // velocity of fragmenting drop - eq (20)
        scalar Vd = Urmag*rho12*(B1_*taubBar + B2_*sqr(taubBar));
 
        // maximum stable diameter - eq (33)
        scalar Vd1 = sqr(1.0 - Vd/Urmag);
        Vd1 = max(Vd1, SMALL);
        scalar dStable = Wec*sigma/(Vd1*rhoc*sqr(Urmag));
 
        if (d < dStable)
        {
            // droplet diameter already stable = no break-up
            // - do not update d and nParticle
            return false;
        }
        else
        {
            scalar semiMass = nParticle*pow3(d);
 
            // invert eq (3) to create a dimensional break-up time
            scalar taub = taubBar*d/(Urmag*rho12);
 
            // update droplet diameter according to the rate eq (implicitly)
            scalar frac = dt/taub;
            d = (d + frac*dStable)/(1.0 + frac);
 
            // correct the number of particles to conserve mass
            nParticle = semiMass/pow3(d);
        }
    }
 
    return false;
}
 
 
// ************************************************************************* //