Code of the Week #34: pressureInletVelocity

OpenFOAM
1

#201921

之前，我们讨论过 inletOutlet 边界，提到， inletOutlet 基本上与 zeroGradient 相同，但是，如果该边界的网格的速度指向内部时，其设置为 fixedValue (backward flow). fixedValue 的值是 inletValue . 而 pressureInletVelocity 是指，在压力已知的边界上，入流速度是通过边界上的通量来计算的。设置的格式为

    pB
    {
        type            pressureInletVelocity;
        phi             phi;
        rho             rho;
        value           uniform 0;    // 边界上压力的大小
    }

最近，我们一直在聊边界的事，边界上四个系数是如何确定的呢？代码位于 src/finiteVolume/fields/fvPatchFields/derived/pressureInletVelocity/pressureInletVelocityFvPatchVectorField.C：

void Foam::pressureInletVelocityFvPatchVectorField::updateCoeffs()
{
    if (updated())
    {
        return;
    }

    const surfaceScalarField& phi =
        db().lookupObject<surfaceScalarField>(phiName_);

    const fvsPatchField<scalar>& phip =
        patch().patchField<surfaceScalarField, scalar>(phi);

    tmp<vectorField> n = patch().nf();                      // 法向量
    const Field<scalar>& magS = patch().magSf();

    if (phi.dimensions() == dimVelocity*dimArea)            // 运算操作
    { 
        operator==(n*phip/magS);                            // 法向量*通量/面积
    }
    else if (phi.dimensions() == dimDensity*dimVelocity*dimArea)
    {
        const fvPatchField<scalar>& rhop =
            patch().lookupPatchField<volScalarField, scalar>(rhoName_);

        operator==(n*phip/(rhop*magS));                     // 法向量*通量/密度/面积
    } 
    else
    {
        FatalErrorInFunction
            << "dimensions of phi are not correct"
            << "\n    on patch " << this->patch().name()
            << " of field " << this->internalField().name()
            << " in file " << this->internalField().objectPath()
            << exit(FatalError);
    }

    fixedValueFvPatchVectorField::updateCoeffs();
}

但是从头文件看到，pressureInletVelocity 继承自 fixedValue

class pressureInletVelocityFvPatchVectorField
:
    public fixedValueFvPatchVectorField
{
    // Private data

        //- Flux field name
        word phiName_;

        //- Density field name
        word rhoName_;


public:

    //- Runtime type information
    TypeName("pressureInletVelocity");
    ...