supersonicFreestreamFvPatchVectorField.C

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#include "supersonicFreestreamFvPatchVectorField.H"
#include "addToRunTimeSelectionTable.H"
#include "fvPatchFieldMapper.H"
#include "volFields.H"

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

Foam::supersonicFreestreamFvPatchVectorField::
supersonicFreestreamFvPatchVectorField
(
    const fvPatch& p,
    const DimensionedField<vector, volMesh>& iF
)
:
    mixedFvPatchVectorField(p, iF),
    TName_("T"),
    pName_("p"),
    psiName_("thermo:psi"),
    UInf_(Zero),
    pInf_(0),
    TInf_(0),
    gamma_(0)
{
    refValue() = patchInternalField();
    refGrad() = Zero;
    valueFraction() = 1;
}


Foam::supersonicFreestreamFvPatchVectorField::
supersonicFreestreamFvPatchVectorField
(
    const fvPatch& p,
    const DimensionedField<vector, volMesh>& iF,
    const dictionary& dict
)
:
    mixedFvPatchVectorField(p, iF),
    TName_(dict.lookupOrDefault<word>("T", "T")),
    pName_(dict.lookupOrDefault<word>("p", "p")),
    psiName_(dict.lookupOrDefault<word>("psi", "thermo:psi")),
    UInf_(dict.lookup("UInf")),
    pInf_(dict.lookup<scalar>("pInf")),
    TInf_(dict.lookup<scalar>("TInf")),
    gamma_(dict.lookup<scalar>("gamma"))
{
    if (dict.found("value"))
    {
        fvPatchField<vector>::operator=
        (
            vectorField("value", dict, p.size())
        );
    }
    else
    {
        fvPatchField<vector>::operator=(patchInternalField());
    }

    refValue() = *this;
    refGrad() = Zero;
    valueFraction() = 1;

    if (pInf_ < small)
    {
        FatalIOErrorInFunction
        (
            dict
        )   << "    unphysical pInf specified (pInf <= 0.0)"
            << "\n    on patch " << this->patch().name()
            << " of field " << this->internalField().name()
            << " in file " << this->internalField().objectPath()
            << exit(FatalIOError);
    }
}


Foam::supersonicFreestreamFvPatchVectorField::
supersonicFreestreamFvPatchVectorField
(
    const supersonicFreestreamFvPatchVectorField& ptf,
    const fvPatch& p,
    const DimensionedField<vector, volMesh>& iF,
    const fvPatchFieldMapper& mapper
)
:
    mixedFvPatchVectorField(ptf, p, iF, mapper),
    TName_(ptf.TName_),
    pName_(ptf.pName_),
    psiName_(ptf.psiName_),
    UInf_(ptf.UInf_),
    pInf_(ptf.pInf_),
    TInf_(ptf.TInf_),
    gamma_(ptf.gamma_)
{}


Foam::supersonicFreestreamFvPatchVectorField::
supersonicFreestreamFvPatchVectorField
(
    const supersonicFreestreamFvPatchVectorField& sfspvf,
    const DimensionedField<vector, volMesh>& iF
)
:
    mixedFvPatchVectorField(sfspvf, iF),
    TName_(sfspvf.TName_),
    pName_(sfspvf.pName_),
    psiName_(sfspvf.psiName_),
    UInf_(sfspvf.UInf_),
    pInf_(sfspvf.pInf_),
    TInf_(sfspvf.TInf_),
    gamma_(sfspvf.gamma_)
{}


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

void Foam::supersonicFreestreamFvPatchVectorField::updateCoeffs()
{
    if (!size() || updated())
    {
        return;
    }

    const fvPatchField<scalar>& pT =
        patch().lookupPatchField<volScalarField, scalar>(TName_);

    const fvPatchField<scalar>& pp =
        patch().lookupPatchField<volScalarField, scalar>(pName_);

    const fvPatchField<scalar>& ppsi =
        patch().lookupPatchField<volScalarField, scalar>(psiName_);

    // Need R of the free-stream flow.  Assume R is independent of location
    // along patch so use face 0
    scalar R = 1.0/(ppsi[0]*pT[0]);

    scalar MachInf = mag(UInf_)/sqrt(gamma_*R*TInf_);

    if (MachInf < 1.0)
    {
        FatalErrorInFunction
            << "\n    on patch " << this->patch().name()
            << " of field " << this->internalField().name()
            << " in file " << this->internalField().objectPath()
            << exit(FatalError);
    }

    vectorField& Up = refValue();
    valueFraction() = 1;

    // get the near patch internal cell values
    const vectorField U(patchInternalField());


    // Find the component of U normal to the free-stream flow and in the
    // plane of the free-stream flow and the patch normal

    // Direction of the free-stream flow
    vector UInfHat = UInf_/mag(UInf_);

    // Normal to the plane defined by the free-stream and the patch normal
    tmp<vectorField> nnInfHat = UInfHat ^ patch().nf();

    // Normal to the free-stream in the plane defined by the free-stream
    // and the patch normal
    const vectorField nHatInf(nnInfHat ^ UInfHat);

    // Component of U normal to the free-stream in the plane defined by the
    // free-stream and the patch normal
    const vectorField Un(nHatInf*(nHatInf & U));

    // The tangential component is
    const vectorField Ut(U - Un);

    // Calculate the Prandtl-Meyer function of the free-stream
    scalar nuMachInf =
        sqrt((gamma_ + 1)/(gamma_ - 1))
       *atan(sqrt((gamma_ - 1)/(gamma_ + 1)*(sqr(MachInf) - 1)))
      - atan(sqr(MachInf) - 1);


    // Set the patch boundary condition based on the Mach number and direction
    // of the flow dictated by the boundary/free-stream pressure difference

    forAll(Up, facei)
    {
        if (pp[facei] >= pInf_) // If outflow
        {
            // Assume supersonic outflow and calculate the boundary velocity
            // according to ???

            scalar fpp =
                sqrt(sqr(MachInf) - 1)
               /(gamma_*sqr(MachInf))*mag(Ut[facei])*log(pp[facei]/pInf_);

            Up[facei] = Ut[facei] + fpp*nHatInf[facei];

            // Calculate the Mach number of the boundary velocity
            scalar Mach = mag(Up[facei])/sqrt(gamma_/ppsi[facei]);

            if (Mach <= 1) // If subsonic
            {
                // Zero-gradient subsonic outflow

                Up[facei] = U[facei];
                valueFraction()[facei] = 0;
            }
        }
        else // if inflow
        {
            // Calculate the Mach number of the boundary velocity
            // from the boundary pressure assuming constant total pressure
            // expansion from the free-stream
            scalar Mach =
                sqrt
                (
                    (2/(gamma_ - 1))*(1 + ((gamma_ - 1)/2)*sqr(MachInf))
                   *pow(pp[facei]/pInf_, (1 - gamma_)/gamma_)
                  - 2/(gamma_ - 1)
                );

            if (Mach > 1) // If supersonic
            {
                // Supersonic inflow is assumed to occur according to the
                // Prandtl-Meyer expansion process

                scalar nuMachf =
                    sqrt((gamma_ + 1)/(gamma_ - 1))
                   *atan(sqrt((gamma_ - 1)/(gamma_ + 1)*(sqr(Mach) - 1)))
                  - atan(sqr(Mach) - 1);

                scalar fpp = (nuMachInf - nuMachf)*mag(Ut[facei]);

                Up[facei] = Ut[facei] + fpp*nHatInf[facei];
            }
            else // If subsonic
            {
                FatalErrorInFunction
                    << "unphysical subsonic inflow has been generated"
                    << "\n    on patch " << this->patch().name()
                    << " of field " << this->internalField().name()
                    << " in file "
                    << this->internalField().objectPath()
                    << exit(FatalError);
            }
        }
    }

    mixedFvPatchVectorField::updateCoeffs();
}


void Foam::supersonicFreestreamFvPatchVectorField::write(Ostream& os) const
{
    fvPatchVectorField::write(os);
    writeEntryIfDifferent<word>(os, "T", "T", TName_);
    writeEntryIfDifferent<word>(os, "p", "p", pName_);
    writeEntryIfDifferent<word>(os, "psi", "thermo:psi", psiName_);
    writeEntry(os, "UInf", UInf_);
    writeEntry(os, "pInf", pInf_);
    writeEntry(os, "TInf", TInf_);
    writeEntry(os, "gamma", gamma_);
    writeEntry(os, "value", *this);
}


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

namespace Foam
{
    makePatchTypeField
    (
        fvPatchVectorField,
        supersonicFreestreamFvPatchVectorField
    );
}

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