[sharonyue]

Hi guys,

I have a volTensorField mu. I wanna use diag() function to get a voldiagTensorField diagmu. So mu is a tensorField, diagmu is a vectorField. The code is as follows:

    volTensorField mu
    (
        IOobject
        (
            "mu",
            runTime.timeName(),
            mesh,
            IOobject::READ_IF_PRESENT
        ),
        U * L //U, L is vectors.
    );
    mu.oldTime();
    
    voldiagTensorField diagmu
    (
        IOobject
        (
            "diagmu",
            runTime.timeName(),
            mesh,
            IOobject::READ_IF_PRESENT
        ),
        diag(mu)
    );
    diagmu.oldTime();

But it says:

voldiagTensorField was not declared in this scope

Whats going on? Any ideas? Thanks.

[Lieven]

The class voldiagTensorField does not exist in openfoam. So you are trying to create an object of a class that doesn't exist. Therefore the error...

[sharonyue]

Originally Posted by Lieven

The class voldiagTensorField does not exist in openfoam. So you are trying to create an object of a class that doesn't exist. Therefore the error...

Thanks, I will try another way.

[Lieven]

In fact, the class you are looking for does exist i.e. volVectorField. So is this maybe close to what to achieve:

volTensorField mu
(
    IOobject
    (
        "mu",
        runTime.timeName(),
        mesh,
        IOobject::READ_IF_PRESENT
    ),
    U * L //U, L is vectors.
);

volVectorField muDiag
(
    IOobject
    (
        "muDiag",
        runTime.timeName(),
        mesh,
        IOobject::READ_IF_PRESENT
    ),
    mesh,
    dimensionedVector("zero",mu.dimensions(),vector::zero)
);

forAll(muDiag,cellI)
{
    muDiag[cellI] = mu[cellI].diag();
}

This is just from the head so I don't promise it compiles immediately.

Cheers,

Lieven