CFD Online Discussion Forums - create volTensorField out of volScalarFields

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create volTensorField out of volScalarFields

Hello everybody,
I want to create a volTensorField out of a couple of volScalarFields. The tensor should look (for example) like this JacobiMatrix=(m1, m2+m1, 0, m5*m3, m4, 0, m0, m2/m1, m2).

The Moments m0-m5 are defined like this

Code:

        Info<< "Reading field m0" << endl;

        volScalarField m0

        (

                IOobject

                (

                        "m0",

                        runTime.timeName(),

                        mesh,

                        IOobject::MUST_READ,

                        IOobject::AUTO_WRITE

                ),

                mesh

        );

I have tried a lot of things, but I do not manage to create the Tensor.
For example:

Code:

        Info<< "Define tensorfield jacobiMatrix" << endl;

        volTensorField jacobiMatrix

        (

                IOobject

                (

                        "jacobiMatrix",

                        runTime.timeName(),

                        mesh,

                        IOobject::NO_READ,

                        IOobject::NO_WRITE

                ),

                mesh,

                dimensionedTensor

                (

                        "zero",

                        dimensionSet(0, 0, 0, 0, 0, 0, 0),

                        tensor::zero

                )

        );

and

Code:

jacobiMatrix.component(0) = m1;

jacobiMatrix.component(1) = m2+m1;

…

The Solver is compiling, but when I use it, an error message appears.

Quote:

--> FOAM FATAL ERROR:
attempted to assign to a const reference to constant object

Does anyone know, how I could create a volTensorField out of the volScalarFields?

You could do a loop over all cells and then compute your components like:

Code:

// const Foam::cellList cells = mesh.cells()

forAll(cells,cellI)

{

JacobiMatrix[cellI].component(0) = m1[cellI]+m2[cellI];

// same for all the others

}

This probably no good style but it should work.

Best Regards
Jim

Thanks a lot, it is working.
But I have to write
forAll(mesh.cells(),cellI)
{...

I already read that it's not a good style. But I did not find an answer on the question, how a good style would look like.

I know this is an old post, but did you (or anyone else) find a more compact solution to this problem? Would be much appreciated!

What you're looking for here is the replace() member function:

Code:

jacobiMatrix.replace(0, m0);

jacobiMatrix.replace(1, m1);

jacobiMatrix.replace(2, m2);

...

...

jacobiMatrix.replace(8, m8);

No need to loop over all cells.