SpalartAllmaras.C

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    Copyright (C) 2019-2021 OpenCFD Ltd.
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#include "SpalartAllmaras.H"
#include "fvOptions.H"
#include "bound.H"
#include "wallDist.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace RASModels
{
 
// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::chi() const
{
    return nuTilda_/this->nu();
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::fv1
(
    const volScalarField& chi
) const
{
    const volScalarField chi3(pow3(chi));
 
    return chi3/(chi3 + pow3(Cv1_));
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField::Internal> SpalartAllmaras<BasicTurbulenceModel>::fv2
(
    const volScalarField::Internal& chi,
    const volScalarField::Internal& fv1
) const
{
    return scalar(1) - chi/(scalar(1) + chi*fv1);
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField::Internal> SpalartAllmaras<BasicTurbulenceModel>::Stilda()
const
{
    const volScalarField chi(this->chi());
 
    const volScalarField fv1(this->fv1(chi));
 
    const volScalarField::Internal Omega
    (
        ::sqrt(scalar(2))*mag(skew(fvc::grad(this->U_)().v()))
    );
 
    return
    (
        max
        (
            Omega + fv2(chi(), fv1())*nuTilda_()/sqr(kappa_*y_),
            Cs_*Omega
        )
    );
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField::Internal> SpalartAllmaras<BasicTurbulenceModel>::fw
(
    const volScalarField::Internal& Stilda
) const
{
    const volScalarField::Internal r
    (
        min
        (
            nuTilda_
           /(
               max
               (
                   Stilda,
                   dimensionedScalar(Stilda.dimensions(), SMALL)
               )
              *sqr(kappa_*y_)
            ),
            scalar(10)
        )
    );
 
    const volScalarField::Internal g(r + Cw2_*(pow6(r) - r));
 
    return
        g*pow
        (
            (scalar(1) + pow6(Cw3_))/(pow6(g) + pow6(Cw3_)),
            scalar(1)/scalar(6)
        );
}
 
 
template<class BasicTurbulenceModel>
void SpalartAllmaras<BasicTurbulenceModel>::correctNut()
{
    this->nut_ = nuTilda_*this->fv1(this->chi());
    this->nut_.correctBoundaryConditions();
    fv::options::New(this->mesh_).correct(this->nut_);
 
    BasicTurbulenceModel::correctNut();
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
template<class BasicTurbulenceModel>
SpalartAllmaras<BasicTurbulenceModel>::SpalartAllmaras
(
    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
    ),
 
    sigmaNut_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "sigmaNut",
            this->coeffDict_,
            scalar(2)/scalar(3)
        )
    ),
    kappa_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "kappa",
            this->coeffDict_,
            0.41
        )
    ),
 
    Cb1_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cb1",
            this->coeffDict_,
            0.1355
        )
    ),
    Cb2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cb2",
            this->coeffDict_,
            0.622
        )
    ),
    Cw1_(Cb1_/sqr(kappa_) + (scalar(1) + Cb2_)/sigmaNut_),
    Cw2_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cw2",
            this->coeffDict_,
            0.3
        )
    ),
    Cw3_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cw3",
            this->coeffDict_,
            2.0
        )
    ),
    Cv1_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cv1",
            this->coeffDict_,
            7.1
        )
    ),
    Cs_
    (
        dimensioned<scalar>::getOrAddToDict
        (
            "Cs",
            this->coeffDict_,
            0.3
        )
    ),
 
    nuTilda_
    (
        IOobject
        (
            "nuTilda",
            this->runTime_.timeName(),
            this->mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        this->mesh_
    ),
 
    y_(wallDist::New(this->mesh_).y())
{
    if (type == typeName)
    {
        this->printCoeffs(type);
    }
}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
template<class BasicTurbulenceModel>
bool SpalartAllmaras<BasicTurbulenceModel>::read()
{
    if (eddyViscosity<RASModel<BasicTurbulenceModel>>::read())
    {
        sigmaNut_.readIfPresent(this->coeffDict());
        kappa_.readIfPresent(this->coeffDict());
 
        Cb1_.readIfPresent(this->coeffDict());
        Cb2_.readIfPresent(this->coeffDict());
        Cw1_ = Cb1_/sqr(kappa_) + (scalar(1) + Cb2_)/sigmaNut_;
        Cw2_.readIfPresent(this->coeffDict());
        Cw3_.readIfPresent(this->coeffDict());
        Cv1_.readIfPresent(this->coeffDict());
        Cs_.readIfPresent(this->coeffDict());
 
        return true;
    }
 
    return false;
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::DnuTildaEff() const
{
    return tmp<volScalarField>::New
    (
        "DnuTildaEff",
        (nuTilda_ + this->nu())/sigmaNut_
    );
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::k() const
{
    // (B:Eq. 4.50)
    const scalar Cmu = 0.09;
 
    return tmp<volScalarField>::New
    (
        IOobject
        (
            IOobject::groupName("k", this->alphaRhoPhi_.group()),
            this->runTime_.timeName(),
            this->mesh_
        ),
        cbrt(this->fv1(this->chi()))
        *nuTilda_
        *::sqrt(scalar(2)/Cmu)
        *mag(symm(fvc::grad(this->U_))),
        this->nut_.boundaryField().types()
    );
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::epsilon() const
{
    // (B:Eq. 4.50)
    const scalar Cmu = 0.09;
    const dimensionedScalar nutSMALL(sqr(dimLength)/dimTime, SMALL);
 
    return tmp<volScalarField>::New
    (
        IOobject
        (
            IOobject::groupName("epsilon", this->alphaRhoPhi_.group()),
            this->runTime_.timeName(),
            this->mesh_
        ),
        pow(this->fv1(this->chi()), 0.5)
        *pow(::sqrt(Cmu)*this->k(), 2)
        /(nuTilda_ + this->nut_ + nutSMALL),
        this->nut_.boundaryField().types()
    );
}
 
 
template<class BasicTurbulenceModel>
tmp<volScalarField> SpalartAllmaras<BasicTurbulenceModel>::omega() const
{
    // (P:p. 384)
    const scalar betaStar = 0.09;
    const dimensionedScalar k0(sqr(dimLength/dimTime), SMALL);
 
    return tmp<volScalarField>::New
    (
        IOobject
        (
            IOobject::groupName("omega", this->alphaRhoPhi_.group()),
            this->runTime_.timeName(),
            this->mesh_
        ),
        this->epsilon()/(betaStar*(this->k() + k0)),
        this->nut_.boundaryField().types()
    );
}
 
 
template<class BasicTurbulenceModel>
void SpalartAllmaras<BasicTurbulenceModel>::correct()
{
    if (!this->turbulence_)
    {
        return;
    }
 
    {
        // Construct local convenience references
        const alphaField& alpha = this->alpha_;
        const rhoField& rho = this->rho_;
        const surfaceScalarField& alphaRhoPhi = this->alphaRhoPhi_;
        fv::options& fvOptions(fv::options::New(this->mesh_));
 
        eddyViscosity<RASModel<BasicTurbulenceModel>>::correct();
 
        const volScalarField::Internal Stilda(this->Stilda());
 
        tmp<fvScalarMatrix> nuTildaEqn
        (
            fvm::ddt(alpha, rho, nuTilda_)
          + fvm::div(alphaRhoPhi, nuTilda_)
          - fvm::laplacian(alpha*rho*DnuTildaEff(), nuTilda_)
          - Cb2_/sigmaNut_*alpha*rho*magSqr(fvc::grad(nuTilda_))
         ==
            Cb1_*alpha()*rho()*Stilda*nuTilda_()
          - fvm::Sp(Cw1_*alpha()*rho()*fw(Stilda)*nuTilda_()/sqr(y_), nuTilda_)
          + fvOptions(alpha, rho, nuTilda_)
        );
 
        nuTildaEqn.ref().relax();
        fvOptions.constrain(nuTildaEqn.ref());
        solve(nuTildaEqn);
        fvOptions.correct(nuTilda_);
        bound(nuTilda_, dimensionedScalar(nuTilda_.dimensions(), Zero));
        nuTilda_.correctBoundaryConditions();
    }
 
    // Update nut with latest available nuTilda
    correctNut();
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace RASModels
} // End namespace Foam
 
// ************************************************************************* //