[niklas]

you could try to implement it implicitly
fvc::laplacian(delta*F,Psat) = fvc::div( delta*F*grad(Psat) )

volVectorField dps = delta * fvc::grad(Psat);
surfaceScalarField dpsf = fvc::interpolate(dps) & mesh.Sf();

then you can view the dps field as a 'convective' change of F due to the Psat gradient
and rewrite it like this

fvc::laplacian(delta*F,Psat) = fvm::div(dpsf, F)


...should work

[fabian_roesler]

Hi

That's a pitty. But the code of niklas seems to be promissing. Ricardo, I didn't get your approach in total. Could you explain it in a little more detail? Especially the part of the lduAddressing.

Regards

Fabian

[Ricardo]

Originally Posted by niklas

fvc::laplacian(delta*F,Psat) = fvm::div(dpsf, F)
...should work

implementation to solver >> solve (fvm::ddt(dw,F)==fvm::laplacian(lambdaD*Psat,F)+fv m::div(dpsf, F)); doen't works, too

Originally Posted by fabian_roesler

Hi

That's a pitty. But the code of niklas seems to be promissing. Ricardo, I didn't get your approach in total. Could you explain it in a little more detail? Especially the part of the lduAddressing.

Regards

Fabian

This is my code, but it I am still working ...

a part of code ...

    float tdelta = 1.0;
    float tdeltaN = 1.0;
    
    float fdelta = 1.0;
    float fdeltaN = 1.0;

    double relFaktor = 1.0;
    int iter = 0;
    
    #include "boundaryCalculation.H"
    
    do 
    {

    Tt = T;
    
    #include "heatParameters.H"

    solve
            (
               fvm::ddt(cap,T)==fvm::laplacian(lambda, T)//+hv*fvc::laplacian(lambdaD, Psat*F)
         );

    T=(relFaktor)*T+(1-relFaktor)*Tt;
    
    tdeltaN=diffFields(T,Tt);

    #include "saturatedpressure.H"
    #include "moistureParameters.H"


    fvScalarMatrix mat1
    (
          fvm::laplacian(lambdaD,F)
     );

    
    label Nc = mesh.nCells(); //Total number of cells
    
    // Diagonal coefficients calculation
        for(label i=0; i<Nc; i++)
        {
          mat1.diag()[i]*=Psat[i];
        }
        
    //Off-diagonal coefficients calculation
        for(label faceI=0; faceI<mat1.lduAddr().lowerAddr().size(); faceI++)
        {
    mat1.lower()[faceI]*=Psat[mesh.faceOwner()[faceI]];
      mat1.upper()[faceI]*=Psat[mesh.faceNeighbour()[faceI]];
        }


      dimensionedScalar Pa ("Pa",dimensionSet(1,-1,-2,0,0,0,0), 1.0 );

    mat1*=Pa;
 
    solve
        (
            fvm::ddt(dw,F)==mat1
    //fvm::laplacian(lambdaD*Psat,F)//+fvc::laplacian(dT,T)// //  
         );
    
    F=(relFaktor)*F + (1-relFaktor)*Ft;

    fdeltaN=diffFields(F,Ft);
     
    #include "w_prepocet.H"
    iter++;
    
    if (iter==1)
    {
    tdelta=tdeltaN;
    fdelta=fdeltaN;
    }

    if ((tdeltaN>tdelta) || (fdeltaN>fdelta))
    {
    relFaktor=relFaktor/2;
    T=(relFaktor)*T+(1-relFaktor)*Tt;
    F=(relFaktor)*F + (1-relFaktor)*Ft;
    }
    
    } while (((tdeltaN>maxDeltaT) || (fdeltaN>maxDeltaH)) && iter < maxIter);

my approach to laplacian(labmbdaD,F*Psat) is in code, maybe for expert it could be ridiculous , but I am working with openFoam and C++ 2 weeks, and this code gives some "expected" values. Other approach gives unstability or doesn't work...

I tried next approach, rewrite partial pressure by gradient of temperature, it seems, that gives similar values like lduaddressing script

I don't know where is problem, I have to check all functions, material parameters and other properties again,...

thanks to all for support and advices
Richard

[niklas]

you REALLY need to be more specific when you say 'it doesnt work'.

[Ricardo]

I was wrong , It works, but obtained values ...

dimensions [0 0 0 0 0 0 0];

internalField nonuniform List<scalar>
4000
(
-1.35814e-10
4.58031e-11
4.58031e-11
4.58031e-11
4.5803e-11
4.58031e-11
4.58031e-11
4.58031e-11
-1.82592e-10
-1.77054e-12
-2.23032e-11

So it seems (two scheme unstable), that a problem could be somewhere else,

Is right using parameters (lambda), stored as volScalaField and (ununiform field) calculated in each step equation by this way? (fvm::laplacian(lambda,T)) Is it interpreted correctly to scheme or is used average values?

Thanks
Richard

[quarkz]

Originally Posted by fabian_roesler

Hi,

when psat is a function of temperature, you are not allowed to pull it out of the gradient in the laplacian function. But you could use the chain rule to get an implicit term of F and an explicit term of psat. Here we go:

Eqn (1): This is your starting point

    fvm::ddt(dw,F) + fvm::laplacian(delta,psat*F)

Eqn (2): Split the gradient term

    fvm::ddt(dw,F) + fvc::div(delta*F*fvc::grad(psat) + delta*psat*fvc::grad(F))

Eqn (3): Split the divergence term

    fvm::ddt(dw,F) + fvc::div(delta*F*fvc::grad(psat)) + fvm::div(delta*psat*fvc::grad(F))

Eqn (4): form the last two terms into laplacians again

    fvm::ddt(dw,F) + fvc::laplacian(delta*F,psat) + m::laplacian(delta*psat,F)

Eqn 4 should work for you. Try it out.

Regards

Fabian

Hi, anyone manage to solve the problem?

I face similar problem whereby I need to convert

fvm::laplacian((alpha*rho*DkEff(F1)), k_)

to

fvm::laplacian((alpha*DkEff(F1)), rho*k_)

I used eqn4 as recommended to get:

fvm::laplacian((alpha*rho*DkEff(F1)), k_) + fvc::laplacian((alpha*k_*DkEff(F1)), rho)

but seems like I can't place rho there in:

fvc::laplacian((alpha*k_*DkEff(F1)), rho)

The error is "error: no matching function for call to ‘laplacian(Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >, const rhoField&)’"

Another error is "note: template argument deduction/substitution failed"

Any idea how to solver it? Must been trying to solve it for a month.

Thanks