[keepfit]

Hi Foamers,

I have a question about how to write out a volScalarField derived from existing field:

The existing volScalarFields are :

...
    volScalarField alpha1
    (
        IOobject
        (
            "alpha1",
            runTime.timeName(),
            mesh,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        mesh
    );
....

    volScalarField voidfraction  // volume fraction of fluid, the rest is solid phase within one cell
    (
        IOobject
        (
            "voidfraction",
            runTime.timeName(),
            mesh,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        mesh
    );

Now I want to visualize a new volScalarField defined by alpha1*voidfraction:

    volScalarField alpha1Voidfraction
    (
        IOobject
        (
            "alpha1",
            runTime.timeName(),
            mesh,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        alpha1*voidfraction
        //mesh
    );

Is the definition right? An "alpha1Voidfraction" BC is also defined in folder 0 similar to "alpha1". The simulation goes well, however, no such Field can be selected in paraview.

Basically I just want to write out "alpha1*voidfraction" and "(1-apha1)*voidfraction" everywhere in the fluid domain, does someone have such experiences on this issue? Any advice or recommendation will be highly appreciated.

Cheers,

David

[nimasam]

well, you can use paraView calculator filter to calculate such expression

[Bernhard]

You name the field "alpha1" (in IOobject), this is also what paraview/parafoam shows. Put the correct name here, e.g. "alpha1Voidfraction"

[keepfit]

Originally Posted by Bernhard

You name the field "alpha1" (in IOobject), this is also what paraview/parafoam shows. Put the correct name here, e.g. "alpha1Voidfraction"

thanks for the tip.

It shows perfect in paraview.

However, I couldn't figure out why the volScalarField "alpha1Voidfraction" remains the initial status, even the alpha1 field changes.

Thnaks.

[fumiya]

You need to update the volScalarField "alpha1Voidfraction" in the time loop:

while (simple.loop())
{
    alpha1Voidfraction=alpha1*voidfraction;
}

[jherb]

Very late answer:
For the field alpha1Voidfraction you probably do not want to read it, because it is always calculated as suggested in comment #5. So you should probably change IOobject::MUST_READ to IOobject::NO_READ in the definition of that field.