massRosinRammler.C

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    Copyright (C) 2021 OpenCFD Ltd.
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#include "massRosinRammler.H"
#include "MathFunctions.H"
#include "addToRunTimeSelectionTable.H"

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

namespace Foam
{
namespace distributionModels
{
    defineTypeNameAndDebug(massRosinRammler, 0);
    addToRunTimeSelectionTable(distributionModel, massRosinRammler, dictionary);
}
}

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

Foam::distributionModels::massRosinRammler::massRosinRammler
(
    const dictionary& dict,
    Random& rndGen
)
:
    distributionModel(typeName, dict, rndGen),
    lambda_(distributionModelDict_.getCompat<scalar>("lambda", {{"d", 2106}})),
    n_(distributionModelDict_.get<scalar>("n"))
{
    if (lambda_ < VSMALL || n_ < VSMALL)
    {
        FatalErrorInFunction
            << "Scale/Shape parameter cannot be equal to or less than zero:"
            << "    lambda = " << lambda_
            << "    n = " << n_
            << exit(FatalError);
    }

    check();
}


Foam::distributionModels::massRosinRammler::massRosinRammler
(
    const massRosinRammler& p
)
:
    distributionModel(p),
    lambda_(p.lambda_),
    n_(p.n_)
{}


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

Foam::scalar Foam::distributionModels::massRosinRammler::sample() const
{
    scalar d = 0;
    do
    {
        // (YHD:Inverse of Eq. 10)
        const scalar a = scalar(3)/n_ + scalar(1);
        const scalar cdfA = Math::incGamma_P(a, pow(minValue_/lambda_, n_) );
        const scalar cdfB = Math::incGamma_P(a, pow(maxValue_/lambda_, n_) );

        const scalar u = rndGen_.position<scalar>(cdfA, cdfB);
        const scalar x = Math::invIncGamma(a, u);
        d = lambda_*pow(x, scalar(1)/n_);

    } while (std::isnan(d));

    return d;
}


Foam::scalar Foam::distributionModels::massRosinRammler::meanValue() const
{
    // (YHD:Eqs. 11-12)
    return lambda_*tgamma(scalar(1)/n_ + scalar(1));
}


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