realizableKE.C

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    Copyright (C) 2019-2023 OpenCFD Ltd.
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License
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#include "realizableKE.H"
#include "fvOptions.H"
#include "bound.H"

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

namespace Foam
{
namespace RASModels
{

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

template<class BasicTurbulenceModel>
tmp<volScalarField> realizableKE<BasicTurbulenceModel>::rCmu
(
    const volTensorField& gradU,
    const volScalarField& S2,
    const volScalarField& magS
)
{
    tmp<volSymmTensorField> tS = devSymm(gradU);
    const volSymmTensorField& S = tS();

    volScalarField W
    (
        (2*sqrt(2.0))*((S&S)&&S)
       /(
            magS*S2
          + dimensionedScalar("small", dimensionSet(0, 0, -3, 0, 0), SMALL)
        )
    );

    tS.clear();

    volScalarField phis
    (
        (1.0/3.0)*acos(clamp(sqrt(6.0)*W, scalarMinMax(-1, 1)))
    );
    volScalarField As(sqrt(6.0)*cos(phis));
    volScalarField Us(sqrt(S2/2.0 + magSqr(skew(gradU))));

    return 1.0/(A0_ + As*Us*k_/epsilon_);
}


template<class BasicTurbulenceModel>
void realizableKE<BasicTurbulenceModel>::correctNut
(
    const volTensorField& gradU,
    const volScalarField& S2,
    const volScalarField& magS
)
{
    this->nut_ = rCmu(gradU, S2, magS)*sqr(k_)/epsilon_;
    this->nut_.correctBoundaryConditions();
    fv::options::New(this->mesh_).correct(this->nut_);

    BasicTurbulenceModel::correctNut();
}


template<class BasicTurbulenceModel>
void realizableKE<BasicTurbulenceModel>::correctNut()
{
    tmp<volTensorField> tgradU = fvc::grad(this->U_);
    volScalarField S2(2*magSqr(devSymm(tgradU())));
    volScalarField magS(sqrt(S2));
    correctNut(tgradU(), S2, magS);
}


template<class BasicTurbulenceModel>
tmp<fvScalarMatrix> realizableKE<BasicTurbulenceModel>::kSource() const
{
    return tmp<fvScalarMatrix>::New
    (
        k_,
        dimVolume*this->rho_.dimensions()*k_.dimensions()/dimTime
    );
}


template<class BasicTurbulenceModel>
tmp<fvScalarMatrix> realizableKE<BasicTurbulenceModel>::epsilonSource() const
{
    return tmp<fvScalarMatrix>::New
    (
        epsilon_,
        dimVolume*this->rho_.dimensions()*epsilon_.dimensions()/dimTime
    );
}


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

template<class BasicTurbulenceModel>
realizableKE<BasicTurbulenceModel>::realizableKE
(
    const alphaField& alpha,
    const rhoField& rho,
    const volVectorField& U,
    const surfaceScalarField& alphaRhoPhi,
    const surfaceScalarField& phi,
    const transportModel& transport,
    const word& propertiesName,
    const word& type
)
:
    eddyViscosity<RASModel<BasicTurbulenceModel>>
    (
        type,
        alpha,
        rho,
        U,
        alphaRhoPhi,
        phi,
        transport,
        propertiesName
    ),
    A0_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "A0",
            this->coeffDict_,
            4.0
        )
    ),
    C2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "C2",
            this->coeffDict_,
            1.9
        )
    ),
    sigmak_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "sigmak",
            this->coeffDict_,
            1.0
        )
    ),
    sigmaEps_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "sigmaEps",
            this->coeffDict_,
            1.2
        )
    ),

    k_
    (
        IOobject
        (
            IOobject::groupName("k", U.group()),
            this->runTime_.timeName(),
            this->mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        this->mesh_
    ),
    epsilon_
    (
        IOobject
        (
            IOobject::groupName("epsilon", U.group()),
            this->runTime_.timeName(),
            this->mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        this->mesh_
    )
{
    bound(k_, this->kMin_);
    bound(epsilon_, this->epsilonMin_);

    if (type == typeName)
    {
        this->printCoeffs(type);
    }
}


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

template<class BasicTurbulenceModel>
bool realizableKE<BasicTurbulenceModel>::read()
{
    if (eddyViscosity<RASModel<BasicTurbulenceModel>>::read())
    {
        A0_.readIfPresent(this->coeffDict());
        C2_.readIfPresent(this->coeffDict());
        sigmak_.readIfPresent(this->coeffDict());
        sigmaEps_.readIfPresent(this->coeffDict());

        return true;
    }

    return false;
}


template<class BasicTurbulenceModel>
void realizableKE<BasicTurbulenceModel>::correct()
{
    if (!this->turbulence_)
    {
        return;
    }

    // Local references
    const alphaField& alpha = this->alpha_;
    const rhoField& rho = this->rho_;
    const surfaceScalarField& alphaRhoPhi = this->alphaRhoPhi_;
    const volVectorField& U = this->U_;
    volScalarField& nut = this->nut_;
    fv::options& fvOptions(fv::options::New(this->mesh_));

    eddyViscosity<RASModel<BasicTurbulenceModel>>::correct();

    volScalarField divU(fvc::div(fvc::absolute(this->phi(), U)));

    tmp<volTensorField> tgradU = fvc::grad(U);
    volScalarField S2(2*magSqr(devSymm(tgradU())));
    volScalarField magS(sqrt(S2));

    volScalarField eta(magS*k_/epsilon_);
    volScalarField C1(max(eta/(scalar(5) + eta), scalar(0.43)));

    volScalarField G(this->GName(), nut*(tgradU() && devTwoSymm(tgradU())));

    // Update epsilon and G at the wall
    epsilon_.boundaryFieldRef().updateCoeffs();
    // Push any changed cell values to coupled neighbours
    epsilon_.boundaryFieldRef().template evaluateCoupled<coupledFvPatch>();

    // SAF: limiting thermo->nu(). If psiThermo is used rho might be < 0
    // temporarily when p < 0 then nu < 0 which needs limiting
    volScalarField nuLimited
    (
        max
        (
            this->nu(),
            dimensionedScalar(this->nu()().dimensions(), Zero)
        )
    );

    // Dissipation equation
    tmp<fvScalarMatrix> epsEqn
    (
        fvm::ddt(alpha, rho, epsilon_)
      + fvm::div(alphaRhoPhi, epsilon_)
      - fvm::laplacian(alpha*rho*DepsilonEff(), epsilon_)
     ==
        C1*alpha*rho*magS*epsilon_
      - fvm::Sp
        (
            C2_*alpha*rho*epsilon_/(k_ + sqrt(nuLimited*epsilon_)),
            epsilon_
        )
      + epsilonSource()
      + fvOptions(alpha, rho, epsilon_)
    );

    epsEqn.ref().relax();
    fvOptions.constrain(epsEqn.ref());
    epsEqn.ref().boundaryManipulate(epsilon_.boundaryFieldRef());
    solve(epsEqn);
    fvOptions.correct(epsilon_);
    bound(epsilon_, this->epsilonMin_);


    // Turbulent kinetic energy equation

    tmp<fvScalarMatrix> kEqn
    (
        fvm::ddt(alpha, rho, k_)
      + fvm::div(alphaRhoPhi, k_)
      - fvm::laplacian(alpha*rho*DkEff(), k_)
     ==
        alpha*rho*G
      - fvm::SuSp(2.0/3.0*alpha*rho*divU, k_)
      - fvm::Sp(alpha*rho*epsilon_/k_, k_)
      + kSource()
      + fvOptions(alpha, rho, k_)
    );

    kEqn.ref().relax();
    fvOptions.constrain(kEqn.ref());
    solve(kEqn);
    fvOptions.correct(k_);
    bound(k_, this->kMin_);

    correctNut(tgradU(), S2, magS);
}


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

} // End namespace RASModels
} // End namespace Foam

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