HerschelBulkley.C

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    Copyright (C) 2017 OpenCFD Ltd.
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#include "HerschelBulkley.H"
#include "addToRunTimeSelectionTable.H"
#include "surfaceFields.H"

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

namespace Foam
{
namespace viscosityModels
{
    defineTypeNameAndDebug(HerschelBulkley, 0);

    addToRunTimeSelectionTable
    (
        viscosityModel,
        HerschelBulkley,
        dictionary
    );
}
}


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

Foam::tmp<Foam::volScalarField>
Foam::viscosityModels::HerschelBulkley::calcNu() const
{
    dimensionedScalar tone("tone", dimTime, 1.0);
    dimensionedScalar rtone("rtone", dimless/dimTime, 1.0);

    tmp<volScalarField> sr(strainRate());

    return
    (
        min
        (
            nu0_,
            (tau0_ + k_*rtone*pow(tone*sr(), n_))
           /(max(sr(), dimensionedScalar ("VSMALL", dimless/dimTime, VSMALL)))
        )
    );
}


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

Foam::viscosityModels::HerschelBulkley::HerschelBulkley
(
    const word& name,
    const dictionary& viscosityProperties,
    const volVectorField& U,
    const surfaceScalarField& phi
)
:
    viscosityModel(name, viscosityProperties, U, phi),
    HerschelBulkleyCoeffs_
    (
        viscosityProperties.optionalSubDict(typeName + "Coeffs")
    ),
    k_("k", dimViscosity, HerschelBulkleyCoeffs_),
    n_("n", dimless, HerschelBulkleyCoeffs_),
    tau0_("tau0", dimViscosity/dimTime, HerschelBulkleyCoeffs_),
    nu0_("nu0", dimViscosity, HerschelBulkleyCoeffs_),
    nu_
    (
        IOobject
        (
            name,
            U_.time().timeName(),
            U_.db(),
            IOobject::NO_READ,
            IOobject::AUTO_WRITE
        ),
        calcNu()
    )
{}


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

bool Foam::viscosityModels::HerschelBulkley::read
(
    const dictionary& viscosityProperties
)
{
    viscosityModel::read(viscosityProperties);

    HerschelBulkleyCoeffs_ =
        viscosityProperties.optionalSubDict(typeName + "Coeffs");

    HerschelBulkleyCoeffs_.readEntry("k", k_);
    HerschelBulkleyCoeffs_.readEntry("n", n_);
    HerschelBulkleyCoeffs_.readEntry("tau0", tau0_);
    HerschelBulkleyCoeffs_.readEntry("nu0", nu0_);

    return true;
}


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