LRR.C

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    Copyright (C) 2019-2020 OpenCFD Ltd.
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#include "LRR.H"
#include "fvOptions.H"
#include "wallFvPatch.H"

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

namespace Foam
{
namespace RASModels
{

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

template<class BasicTurbulenceModel>
void LRR<BasicTurbulenceModel>::correctNut()
{
    this->nut_ = this->Cmu_*sqr(k_)/epsilon_;
    this->nut_.correctBoundaryConditions();
    fv::options::New(this->mesh_).correct(this->nut_);

    BasicTurbulenceModel::correctNut();
}


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

template<class BasicTurbulenceModel>
LRR<BasicTurbulenceModel>::LRR
(
    const alphaField& alpha,
    const rhoField& rho,
    const volVectorField& U,
    const surfaceScalarField& alphaRhoPhi,
    const surfaceScalarField& phi,
    const transportModel& transport,
    const word& propertiesName,
    const word& type
)
:
    ReynoldsStress<RASModel<BasicTurbulenceModel>>
    (
        type,
        alpha,
        rho,
        U,
        alphaRhoPhi,
        phi,
        transport,
        propertiesName
    ),

    Cmu_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cmu",
            this->coeffDict_,
            0.09
        )
    ),
    C1_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "C1",
            this->coeffDict_,
            1.8
        )
    ),
    C2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "C2",
            this->coeffDict_,
            0.6
        )
    ),
    Ceps1_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Ceps1",
            this->coeffDict_,
            1.44
        )
    ),
    Ceps2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Ceps2",
            this->coeffDict_,
            1.92
        )
    ),
    Cs_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cs",
            this->coeffDict_,
            0.25
        )
    ),
    Ceps_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Ceps",
            this->coeffDict_,
            0.15
        )
    ),

    wallReflection_
    (
        Switch::getOrAddToDict
        (
            "wallReflection",
            this->coeffDict_,
            true
        )
    ),
    kappa_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "kappa",
            this->coeffDict_,
            0.41
        )
    ),
    Cref1_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cref1",
            this->coeffDict_,
            0.5
        )
    ),
    Cref2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cref2",
            this->coeffDict_,
            0.3
        )
    ),

    k_
    (
        IOobject
        (
            "k",
            this->runTime_.timeName(),
            this->mesh_,
            IOobject::NO_READ,
            IOobject::AUTO_WRITE
        ),
        0.5*tr(this->R_)
    ),
    epsilon_
    (
        IOobject
        (
            "epsilon",
            this->runTime_.timeName(),
            this->mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        this->mesh_
    )
{
    if (type == typeName)
    {
        this->printCoeffs(type);

        this->boundNormalStress(this->R_);
        bound(epsilon_, this->epsilonMin_);
        k_ = 0.5*tr(this->R_);
    }
}


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

template<class BasicTurbulenceModel>
bool LRR<BasicTurbulenceModel>::read()
{
    if (ReynoldsStress<RASModel<BasicTurbulenceModel>>::read())
    {
        Cmu_.readIfPresent(this->coeffDict());
        C1_.readIfPresent(this->coeffDict());
        C2_.readIfPresent(this->coeffDict());
        Ceps1_.readIfPresent(this->coeffDict());
        Ceps2_.readIfPresent(this->coeffDict());
        Cs_.readIfPresent(this->coeffDict());
        Ceps_.readIfPresent(this->coeffDict());

        wallReflection_.readIfPresent("wallReflection", this->coeffDict());
        kappa_.readIfPresent(this->coeffDict());
        Cref1_.readIfPresent(this->coeffDict());
        Cref2_.readIfPresent(this->coeffDict());

        return true;
    }

    return false;
}


template<class BasicTurbulenceModel>
tmp<volSymmTensorField> LRR<BasicTurbulenceModel>::DREff() const
{
    return tmp<volSymmTensorField>
    (
        new volSymmTensorField
        (
            "DREff",
            (Cs_*(this->k_/this->epsilon_))*this->R_ + I*this->nu()
        )
    );
}


template<class BasicTurbulenceModel>
tmp<volSymmTensorField> LRR<BasicTurbulenceModel>::DepsilonEff() const
{
    return tmp<volSymmTensorField>
    (
        new volSymmTensorField
        (
            "DepsilonEff",
            (Ceps_*(this->k_/this->epsilon_))*this->R_ + I*this->nu()
        )
    );
}


template<class BasicTurbulenceModel>
void LRR<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_;
    volSymmTensorField& R = this->R_;
    fv::options& fvOptions(fv::options::New(this->mesh_));

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

    tmp<volTensorField> tgradU(fvc::grad(U));
    const volTensorField& gradU = tgradU();

    volSymmTensorField P(-twoSymm(R & gradU));
    volScalarField G(this->GName(), 0.5*mag(tr(P)));

    // Update epsilon and G at the wall
    epsilon_.boundaryFieldRef().updateCoeffs();

    // Dissipation equation
    tmp<fvScalarMatrix> epsEqn
    (
        fvm::ddt(alpha, rho, epsilon_)
      + fvm::div(alphaRhoPhi, epsilon_)
      - fvm::laplacian(alpha*rho*DepsilonEff(), epsilon_)
     ==
        Ceps1_*alpha*rho*G*epsilon_/k_
      - fvm::Sp(Ceps2_*alpha*rho*epsilon_/k_, epsilon_)
      + 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_);


    // Correct the trace of the tensorial production to be consistent
    // with the near-wall generation from the wall-functions
    const fvPatchList& patches = this->mesh_.boundary();

    forAll(patches, patchi)
    {
        const fvPatch& curPatch = patches[patchi];

        if (isA<wallFvPatch>(curPatch))
        {
            forAll(curPatch, facei)
            {
                label celli = curPatch.faceCells()[facei];
                P[celli] *= min
                (
                    G[celli]/(0.5*mag(tr(P[celli])) + SMALL),
                    1.0
                );
            }
        }
    }

    // Reynolds stress equation
    tmp<fvSymmTensorMatrix> REqn
    (
        fvm::ddt(alpha, rho, R)
      + fvm::div(alphaRhoPhi, R)
      - fvm::laplacian(alpha*rho*DREff(), R)
      + fvm::Sp(C1_*alpha*rho*epsilon_/k_, R)
      ==
        alpha*rho*P
      - (2.0/3.0*(1 - C1_)*I)*alpha*rho*epsilon_
      - C2_*alpha*rho*dev(P)
      + fvOptions(alpha, rho, R)
    );

    // Optionally add wall-refection term
    if (wallReflection_)
    {
        const volVectorField& n_(wallDist::New(this->mesh_).n());
        const volScalarField& y_(wallDist::New(this->mesh_).y());

        const volSymmTensorField reflect
        (
            Cref1_*R - ((Cref2_*C2_)*(k_/epsilon_))*dev(P)
        );

        REqn.ref() +=
            ((3*pow(Cmu_, 0.75)/kappa_)*(alpha*rho*sqrt(k_)/y_))
           *dev(symm((n_ & reflect)*n_));
    }

    REqn.ref().relax();
    fvOptions.constrain(REqn.ref());
    solve(REqn);
    fvOptions.correct(R);

    this->boundNormalStress(R);

    k_ = 0.5*tr(R);

    correctNut();

    // Correct wall shear-stresses when applying wall-functions
    this->correctWallShearStress(R);
}


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

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

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