[klausb]

I want to use an additional value in my custom simpleFoam solver but am not able to read it from the fvSolution dictionary "SIMPLE" section.

The default value should be 4. I tried:

    const int A_ = controlDict_.lookupOrDefault<label> ("A", 4);

With:

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    pRefCell             0;
    pRefValue            0;
    A                    4;
}

I testetd it with const int A_ = 4; for a test and that worked so the problem is reading the value from the fvSolution dictionary. I am using OF7.

[cdegroot]

It looks like you are trying to read the value from controlDict, not fvSolution.

[klausb]

It's not that simple, I tried fvSolution too but the problem seems to be related to the definition of the dictionary to be accessed. Unfortunately I can only find examples related to custom dictionaries, not the standard ones.

[cdegroot]

Fair enough, but aribitrarily trying to read it from the wrong dictionary is sure to fail!

[klausb]

I tried different ways and dictionaries including a custom dictionary. I did it when I used pervious versions of OpenFOAM. Maybe something changed with OF7.

[cdegroot]

Check out the class definition for fvSolution:

Class
    Foam::fvSolution
Description
    Selector class for finite volume solution solution.
    fvMesh is derived from fvSolution so that all fields have access to the
    fvSolution from the mesh reference they hold.

This implies you can get it from the mesh. If you look into fvMesh.C, this is how the fvSolution object is initialized:

fvSolution(static_cast<const objectRegistry&>(*this))

So, I would estimate that you could do the same thing, except replacing *this with an instance of your mesh. I haven't tested, so I'm curious if it would work.

[klausb]

This is, how it worked:

    const word dictName("fvSolution");
    IOdictionary solutionDict
    (
        IOobject
        (
        dictName,
        runTime.system(), //folder where the fvSolution file is located 
        runTime,
        IOobject::MUST_READ
        )
    );

    dictionary& mysimplesubDict = solutionDict.subDict("mySIMPLE"); // subsection where the values are stored

    int A1_ = (mysimplesubDict.lookupOrDefault<label>("A1", 2));
    int A2_ = (mysimplesubDict.lookupOrDefault<label>("A2", 2));