lambdaThixotropic.C

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#include "lambdaThixotropic.H"
#include "fvmDiv.H"
#include "fvmSup.H"
#include "fvModels.H"
#include "fvConstraints.H"
#include "uniformDimensionedFields.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace laminarModels
{
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
template<class BasicMomentumTransportModel>
lambdaThixotropic<BasicMomentumTransportModel>::lambdaThixotropic
(
    const alphaField& alpha,
    const rhoField& rho,
    const volVectorField& U,
    const surfaceScalarField& alphaRhoPhi,
    const surfaceScalarField& phi,
    const viscosity& viscosity
)
:
    linearViscousStress<laminarModel<BasicMomentumTransportModel>>
    (
        typeName,
        alpha,
        rho,
        U,
        alphaRhoPhi,
        phi,
        viscosity
    ),
 
    a_("a", dimless/dimTime, this->coeffDict_),
    b_("b", dimless, this->coeffDict_),
    d_("d", dimless, this->coeffDict_),
    c_("c", pow(dimTime, d_.value() - scalar(1)), this->coeffDict_),
    nu0_("nu0", dimKinematicViscosity, this->coeffDict_),
    nuInf_("nuInf", dimKinematicViscosity, this->coeffDict_),
    K_(1 - sqrt(nuInf_/nu0_)),
    BinghamPlastic_(this->coeffDict_.found("sigmay")),
    sigmay_
    (
        BinghamPlastic_
      ? dimensionedScalar("sigmay", dimPressure/dimDensity, this->coeffDict_)
      : dimensionedScalar("sigmay", dimPressure/dimDensity, 0)
    ),
    residualAlpha_
    (
        dimensioned<scalar>::lookupOrAddToDict
        (
            "residualAlpha",
            this->coeffDict_,
            dimless,
            1e-6
        )
    ),
    lambda_
    (
        IOobject
        (
            this->groupName(typedName("lambda")),
            this->runTime_.name(),
            this->mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        this->mesh_
    ),
 
    nu_
    (
        IOobject
        (
            this->groupName(typedName("nu")),
            this->runTime_.name(),
            this->mesh_,
            IOobject::NO_READ,
            IOobject::AUTO_WRITE
        ),
        calcNu(this->strainRate())
    )
{}
 
 
// * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
template<class BasicMomentumTransportModel>
tmp<volScalarField>
lambdaThixotropic<BasicMomentumTransportModel>::calcNu
(
    const volScalarField& strainRate
) const
{
    tmp<volScalarField> nu
    (
        nuInf_/(sqr(1 - K_*lambda_) + rootVSmall)
    );
 
    // Add optional yield stress contribution to the viscosity
    if (BinghamPlastic_)
    {
        dimensionedScalar sigmaySmall
        (
            "sigmaySmall",
            sigmay_.dimensions(),
            small
        );
 
        // Limit the Bingham viscosity to 100x the thixotropic viscosity
        // for numerical stability
        dimensionedScalar nuMax_("nuMax", 100*nu0_);
 
        nu.ref() = min
        (
            sigmay_/(strainRate + 1e-4*(sigmay_ + sigmaySmall)/nu0_) + nu(),
            nuMax_
        );
    }
 
    return nu;
}
 
 
template<class BasicMomentumTransportModel>
tmp<volScalarField>
lambdaThixotropic<BasicMomentumTransportModel>::strainRate() const
{
    return sqrt(2.0)*mag(symm(fvc::grad(this->U())));
}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
template<class BasicMomentumTransportModel>
bool lambdaThixotropic<BasicMomentumTransportModel>::read()
{
    if (laminarModel<BasicMomentumTransportModel>::read())
    {
        a_.read(this->coeffDict());
        b_.read(this->coeffDict());
        d_.read(this->coeffDict());
 
        c_ = dimensionedScalar
        (
            "c",
            pow(dimTime, d_.value() - scalar(1)),
            this->coeffDict_
        );
 
        nu0_.read(this->coeffDict());
        nuInf_.read(this->coeffDict());
 
        K_ = (1 - sqrt(nuInf_/nu0_));
 
        return true;
    }
    else
    {
        return false;
    }
}
 
 
template<class BasicMomentumTransportModel>
tmp<volScalarField>
lambdaThixotropic<BasicMomentumTransportModel>::nuEff() const
{
    return volScalarField::New
    (
        this->groupName("nuEff"),
        nu_
    );
}
 
 
template<class BasicMomentumTransportModel>
tmp<scalarField>
lambdaThixotropic<BasicMomentumTransportModel>::nuEff
(
    const label patchi
) const
{
    return nu_.boundaryField()[patchi];
}
 
 
template<class BasicMomentumTransportModel>
void lambdaThixotropic<BasicMomentumTransportModel>::correct()
{
    // Local references
    const alphaField& alpha = this->alpha_;
    const rhoField& rho = this->rho_;
    const surfaceScalarField& alphaRhoPhi = this->alphaRhoPhi_;
    const Foam::fvModels& fvModels(Foam::fvModels::New(this->mesh_));
    const Foam::fvConstraints& fvConstraints
    (
        Foam::fvConstraints::New(this->mesh_)
    );
 
    const volScalarField strainRate(this->strainRate());
 
    tmp<fvScalarMatrix> lambdaEqn
    (
        fvm::ddt(alpha, rho, lambda_)
      + fvm::div(alphaRhoPhi, lambda_)
     ==
        alpha()*rho()*a_*pow(1 - lambda_(), b_)
      - fvm::Sp
        (
            rho()
           *(
               alpha()*c_*pow(strainRate(), d_)
             + max(residualAlpha_ - alpha(), dimensionedScalar(dimless, 0))*a_
            ),
            lambda_
        )
      + fvModels.source(alpha, rho, lambda_)
    );
 
    lambdaEqn.ref().relax();
    fvConstraints.constrain(lambdaEqn.ref());
    solve(lambdaEqn);
    fvConstraints.constrain(lambda_);
 
    lambda_.maxMin(scalar(0), scalar(1));
 
    nu_ = calcNu(strainRate);
 
    laminarModel<BasicMomentumTransportModel>::correct();
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace laminarModels
} // End namespace Foam
 
// ************************************************************************* //