[BaselAS]

Hi,
I'm very new to OpenFOAM, and I've been tasked in exporting a certain matrix's data from the solver on each time-step.
I've read Matrices_in_OpenFOAM but unfortunately I didn't fully understand lduaddressing... where can I find more examples on the subject?

as I mentioned, I need to export the matrix's data, meaning I need to loop over all non-zero entries and output the value along with its row-col index. any tips are very much welcomed.

Thanks in advance,
Basel

[hasan_shetabivash]

Dear BaselAS,

LduAddressing keeps the addressing of related cells. In lduMatrix coefficients are stored in three list named diagonal, upper and lower. If you just want to export the fvMatrix data you can simply use << operator for those list. And if you want to have indexing of all the lists you need to loop over all faces. The following example may help you.

  fvScalarMatrix TEqn
    (
        fvm::ddt(T)+
        fvm::laplacian(dimensionedScalar("D", dimensionSet(0,2,-1,0,0,0,0), 1), T)
    );
//Printing diagonal lower and upper lists   
    Info<<TEqn.diag()<<endl;
    Info<<TEqn.lower()<<endl;
    Info<<TEqn.upper()<<endl;
    const labelUList& owner = mesh.owner();
    const labelUList& neighbour = mesh.neighbour();
    Info<<owner<<endl;
    Info<<neighbour<<endl;
    const labelUList& lowerAdd = TEqn.lduAddr().lowerAddr();
    const labelUList& upperAdd = TEqn.lduAddr().upperAddr();
    for(int index=0;index<mesh.cells().size();index++)
    {
        Info<<"Diagonal value"<<TEqn.diag()[index]<<"\tDiagonal index: "<<index<<","<<index<<endl;
    }
    forAll(neighbour, facei)
    {
        Info<<"Lower value: "<<TEqn.lower()[facei]<<"\tLower index: "<<upperAdd[facei]<<","<<lowerAdd[facei]<<endl;
    }
    forAll(neighbour, facei)
    {
        Info<<"Upper value: "<<TEqn.upper()[facei]<<"\tUpper index: "<<lowerAdd[facei]<<","<<upperAdd[facei]<<endl;
    }

Cheers,

[BaselAS]

Originally Posted by hasan_shetabivash

Dear BaselAS,

LduAddressing keeps the addressing of related cells. In lduMatrix coefficients are stored in three list named diagonal, upper and lower. If you just want to export the fvMatrix data you can simply use << operator for those list. And if you want to have indexing of all the lists you need to loop over all faces. The following example may help you.

  fvScalarMatrix TEqn
    (
        fvm::ddt(T)+
        fvm::laplacian(dimensionedScalar("D", dimensionSet(0,2,-1,0,0,0,0), 1), T)
    );
//Printing diagonal lower and upper lists   
    Info<<TEqn.diag()<<endl;
    Info<<TEqn.lower()<<endl;
    Info<<TEqn.upper()<<endl;
    const labelUList& owner = mesh.owner();
    const labelUList& neighbour = mesh.neighbour();
    Info<<owner<<endl;
    Info<<neighbour<<endl;
    const labelUList& lowerAdd = TEqn.lduAddr().lowerAddr();
    const labelUList& upperAdd = TEqn.lduAddr().upperAddr();
    for(int index=0;index<=neighbour.size();index++)
    {
        Info<<"Diagonal value"<<TEqn.diag()[index]<<"\tDiagonal index: "<<index<<","<<index<<endl;
    }
    forAll(neighbour, facei)
    {
        Info<<"Lower value: "<<TEqn.lower()[facei]<<"\tLower index: "<<upperAdd[facei]<<","<<lowerAdd[facei]<<endl;
    }
    forAll(neighbour, facei)
    {
        Info<<"Upper value: "<<TEqn.upper()[facei]<<"\tUpper index: "<<lowerAdd[facei]<<","<<upperAdd[facei]<<endl;
    }

Cheers,

That's fantastic, exactly what I needed!
Thank you very much!