change the k at first grid?

[kimy]

Hi guys,

I would like to change the k value in the first grid near wall by the following formulation:

kc=(U\tau)^2/sqrt(Cmu);

I wrote the code, according to epsilonwallfunction, but I met the problem when I compile it.

derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C: In member function 'virtual void Foam::kOngWallFunctionFvPatchScalarField::updateCo effs()':
derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C:218:120: error: assignment of read-only location '(& k)->Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::<anonymous>.Foam:imensionedField <double, Foam::volMesh>::<anonymous>.Foam::Field<double>::< anonymous>.Foam::List<double>::<anonymous>.Foam::U List<double>:perator[](celli)'
((nutw[facei] + nuw[facei])*magGradUw[facei])*((nutw[facei] + nuw[facei])*magGradUw[facei])/(Cmu25*Cmu2 );

my codes in kwallfunction:
const scalarField& y = turbModel.y()[patchi];
const tmp<volScalarField> tk = turbModel.k();
const volScalarField& k = tk();
const tmp<scalarField> tnuw = turbModel.nu(patchi);
const scalarField& nuw = tnuw();
const tmp<scalarField> tnutw = turbModel.nut(patchi);
const scalarField& nutw = tnutw();
const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];
const scalarField magGradUw(mag(Uw.snGrad()));

forAll(nutw,facei)
{
label celli = patch().faceCells()[facei];

scalar yPlus = Cmu25*y[facei]*sqrt(k[celli])/nuw[facei];



if (yPlus > yPlusLam_)
{


k[celli] =

((nutw[facei] + nuw[facei])*magGradUw[facei])*((nutw[facei] + nuw[facei])*magGradUw[facei])/(Cmu25*Cmu25);

}

[李东岳]

https://dyfluid.coding.net/p/OpenFOAM_dyfluid/d/OpenFOAM_dyfluid/git/tree/master/solver/dyfluidFoam.C 67-73

[kimy]

@东岳 Hi, dongyue. Thanks a lot. I understood this method but can I use it in a kwallfunction? After I tried the code you suggested, the compiling error is mesh not decalred in this scope. If I would like to update the first grid value in the kwallfunction like epsilonwallfunction did, is it possible?

[李东岳]

the compiling error is mesh not decalred in this scope

Looks you used that in a Class. Try to include the following code snippet before you use it:

const fvMesh& mesh = k.mesh();

If I would like to update the first grid value in the kwallfunction like epsilonwallfunction did, is it possible?

Everything is possible as long as it is physical.

[kimy]

@东岳

derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C: In member function 'virtual void Foam::kOngWallFunctionFvPatchScalarField::updateCoeffs()':
derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C:190:40: error: 'class Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >' has no member named 'mesh'
     const fvMesh& mesh = turbModel.k().mesh();

[李东岳]

@kimy 在 change the k at first grid? 中说：

kqRWallFunctions

If p is a fvPatch

const fvMesh& mesh = p.boundaryMesh().mesh();

[kimy]

@东岳

derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C: In member function 'virtual void Foam::kOngWallFunctionFvPatchScalarField::updateCoeffs()':
derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C:204:22: error: 'p' was not declared in this scope
 const fvMesh& mesh = p.boundaryMesh().mesh();
                      ^
derivedFvPatchFields/wallFunctions/kqRWallFunctions/kOngWallFunction/kOngWallFunctionFvPatchScalarField.C:209:28: error: passing 'const volScalarField {aka const Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>}' as 'this' argument discards qualifiers [-fpermissive]
         k.boundaryFieldRef()[patchID] = 0;

[李东岳]

You should highlight you code yourself. Otherwise I need modify it everytime.

The above code runs well if your put it inside the following

template<class Type>
Foam::kqRWallFunctionFvPatchField<Type>::kqRWallFunctionFvPatchField
(
    const kqRWallFunctionFvPatchField& ptf,
    const fvPatch& p,
    const DimensionedField<Type, volMesh>& iF,
    const fvPatchFieldMapper& mapper
)
:
    zeroGradientFvPatchField<Type>(ptf, p, iF, mapper)
{
    const fvMesh& mesh = p.boundaryMesh().mesh();
}

[kimy]

Hi Dongyue, I changed the codes as following, but the result dosn't change, k in the first grid is still not calculated by my formulation. I cannot understand.

 tmp<volScalarField> tk = turbModel.k();
     volScalarField k = tk;

    const tmp<scalarField> tnuw = turbModel.nu(patchi);
    const scalarField& nuw = tnuw();
    const tmp<scalarField> tnutw = turbModel.nut(patchi);
    const scalarField& nutw = tnutw();

    const fvPatchVectorField& Uw = turbModel.U().boundaryField()[patchi];

    const scalarField magGradUw(mag(Uw.snGrad()));

    const scalar Cmu25 = pow025(Cmu_);

    scalarField& kw = *this;
forAll(nutw,facei)
    {
         label celli = patch().faceCells()[facei];

            
            k[celli] =
                
               ((nutw[facei] + nuw[facei])*magGradUw[facei])*((nutw[facei] + nuw[facei])*magGradUw[facei])/(Cmu25*Cmu25);
      }

[kimy]

@东岳 I tried to write these codes in simpleFoam.C,

label patchID = mesh.boundaryMesh().findPatchID("wall");
turbulence->k().boundaryFieldRef()[patchID] = 0;

And I got the error:

newsimpleFoam.C: In function 'int main(int, char**)':
newsimpleFoam.C:77:25: error: 'class Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >' has no member named 'boundaryFieldRef' turbulence->k().boundaryFieldRef()[patchID] = 0;

[李东岳]

Thats a tmp, not a regular volScalarField, try turbulence->k().ref().boundaryFieldRef()[patchID] = 0;