[theBananaTrick]

Hello,


I am taking a look at the functionObject solver scalarTransport. Here, a function exists to create a new field if not found in the dataBase and return a reference to it.

volScalarField& transportedField();

The implementation reads:

Foam::volScalarField& Foam::functionObjects::scalarTransport::transportedField()
{
    if (!foundObject<volScalarField>(fieldName_))
    {
        auto tfldPtr = tmp<volScalarField>::New
        (
            IOobject
            (
                fieldName_,
                mesh_.time().timeName(),
                mesh_,
                IOobject::MUST_READ,
                IOobject::AUTO_WRITE
            ),
            mesh_
        );
        store(fieldName_, tfldPtr);

        if (phaseName_ != "none")
        {
            mesh_.setFluxRequired(fieldName_);
        }
    }

    return lookupObjectRef<volScalarField>(fieldName_);
 }

A pointer to the field is being stored in

store(fieldName_, tfldPtr);

I would like to know the intent of this approach. Is it to be able to access this field from inside the solver?

e.g.,

volScalarField& myTransportedField = mesh.lookupObjectRef<volScalarField>("nameOfmyTransportedField")
Some calculation with this field

Or something else?

Wouldn't it be helpful to have a variable defined inside the functionObject to store the reference to the volScalarField given by the function?

volScalarField& transportedField_ (transportedField())

This way, it wouldn't be necessary to call the function twice (line 205 and 251)

[olesen]

The idea is not some silly handling of local field storage but rather to define/update a field that should be visible outside of the function object. For example, you might want to use a sampled surface function object to sample and write a slice through the field. For any of this to happen, the field has to be globally available - aka objectRegistry

[theBananaTrick]

Originally Posted by olesen

The idea is not some silly handling of local field storage but rather to define/update a field that should be visible outside of the function object. For example, you might want to use a sampled surface function object to sample and write a slice through the field. For any of this to happen, the field has to be globally available - aka objectRegistry

Hello Mr Olesen,


Thank you very much for your insight! Now I know what is the intent!