[openfoammaofnepo]

Dear All,

The following operation is used for average:

fvc::average

But does anybody know how it is defined in Openfoam? I mean what is it based for the averaging operations? Where is it defined in OF?

Thanks.

OFFO

[Hiroshiman]

You can find the definition in :
src/finiteVolume/finiteVolume/fvc/fvcAverage.* It's defined as "Area-weighted average a surfaceField creating a volField".

[openfoammaofnepo]

OK, thank you for your help!

[openfoammaofnepo]

Originally Posted by Hiroshiman

You can find the definition in :
src/finiteVolume/finiteVolume/fvc/fvcAverage.* It's defined as "Area-weighted average a surfaceField creating a volField".

Hi,

In the source files you cited, there are following lines:

    GeometricField<Type, fvPatchField, volMesh>& av = taverage();

    av.internalField() =
    (
        surfaceSum(mesh.magSf()*ssf)/surfaceSum(mesh.magSf())
    )().internalField();

    typename GeometricField<Type, fvPatchField, volMesh>::
    GeometricBoundaryField& bav = av.boundaryField();

    forAll(bav, patchi)
    {
        bav[patchi] = ssf.boundaryField()[patchi];
    }

    av.correctBoundaryConditions();

If I am not making a mistake, then, for each cell, this kind of average is performed on the faces belonging one cell (e.g. 4 faces for tetrahedrons). Thus each cell will have a local averaged value. Thus fvc::average is not global.

[Gang Wang]

Originally Posted by openfoammaofnepo

Hi,

In the source files you cited, there are following lines:

    GeometricField<Type, fvPatchField, volMesh>& av = taverage();

    av.internalField() =
    (
        surfaceSum(mesh.magSf()*ssf)/surfaceSum(mesh.magSf())
    )().internalField();

    typename GeometricField<Type, fvPatchField, volMesh>::
    GeometricBoundaryField& bav = av.boundaryField();

    forAll(bav, patchi)
    {
        bav[patchi] = ssf.boundaryField()[patchi];
    }

    av.correctBoundaryConditions();

If I am not making a mistake, then, for each cell, this kind of average is performed on the faces belonging one cell (e.g. 4 faces for tetrahedrons). Thus each cell will have a local averaged value. Thus fvc::average is not global.

Hi,

I totally agree with you that fvc::average is somewhat performing the averaging on each cell, but as you claimed, how to get the average value from a global scale of the whole computational domain?

Kindly regards,
Gang