[F42]

Hello,


I wrote my own solver based on chtMultiRegionFoam.
Therefore, I read dictionaries from the constant folder. Now I want to use more than one solid and one fluid region but I can't figure out how to acess the dictionaries for an arbitrary number of regions. I'm using of8.



I tried:

    

forAll(solidRegions, i)
{

fvMesh& mesh = solidRegions[i];
 
IOdictionary myProperties
(
    IOobject
    (
        "myProperties",
        mesh.time().constant(),
        mesh,
        IOobject::MUST_READ_IF_MODIFIED,
        IOobject::NO_WRITE
    )
 );
}

When I try to acess the dict properties later on it throws an error saying that myProperties dict is not declared in this scope:

forAll(solidRegions,i)
{

const scalar myScalar = readScalar(myProperties.lookup("myScalar"));
}

When running the solver it throws the error

--> FOAM FATAL ERROR: 

request for dictionary myProperties from objectRegistry solid1 failed available objects of type dictionary are


3
(
fvSchemes
fvSolution
data
)

I was using the solver with only one solid and one fluid region for quite some time. I used "solidRegions[0]" for the object registry and it worked flawlessly. I don't understand why it's not working for i regions.



Any hints about how to use dictionaries in a multi region solver are appreciated. Thanks.

[olesen]

Not really sure how you expect this to work. In the first loop you create and discard "myProperties" several times. At later stage you are hoping to access the variable from a different scope??? Consider the following standard C/C++ (not OpenFOAM-specific):

int foo = 100;
if (true)
{
    int bar = 200;
}

// print results
{
    printf("foo = %d\n", foo);
    printf("bar = %d\n", bar);
}

You will find that "bar" is unknown.

[F42]

Well, I believed that every dictionary "belongs" to a mesh. So while looping through the mesh regions I tried to create the same dictionary for every mesh region. I thought the respecitve dictionaries are only known "inside" their region and could be accessed later on while looping through the mesh regions again .

I want to make use of openFoam's dictionary function and easily define different properties for each physical region for the simulation in the case/constant folder. (basically like it's done with thermophysicalProperties or whatever).


Can you tell me where I did go wrong and how to actually achieve this? Tanks!

[olesen]

Originally Posted by F42

Well, I believed that every dictionary "belongs" to a mesh. So while looping through the mesh regions I tried to create the same dictionary for every mesh region. I thought the respecitve dictionaries are only known "inside" their region and could be accessed later on while looping through the mesh regions again .

I want to make use of openFoam's dictionary function and easily define different properties for each physical region for the simulation in the case/constant folder. (basically like it's done with thermophysicalProperties or whatever).

Can you tell me where I did go wrong and how to actually achieve this? Tanks!

If you want an IOdictionary (or any other regIOobject) to be registered to a mesh region, then you typically to check that it doesn't already exist on the registry.
You have the possibility to have the registered objects stored externally to the registry or actually stored on the registry. In your original code example, you added have "myProperties" as a local variable, which is indeed registered on the objectRegistry, but since that variable is local, it removes itself from the registry when it goes out of scope.

So one possiblity:

PtrList<IOdictionary> allMyProperties(solidRegions.size());

forAll(solidRegions, regioni)
{
    auto& mesh = solidRegions[regioni];
    allMyProperties.set
    (
        regioni,
        new IOdictionary
        (
             IOobject
             (
                  "myProperties",
                    mesh.time().constant(),
                    mesh,
                    IOobject::MUST_READ_IF_MODIFIED,
                    IOobject::NO_WRITE
             )
        )
    );
}

This is the simplest. If you want to store directly on the registry, you will need "store" instead of using the PtrList, but I think this solution is simpler for your needs.

[F42]

Thank you! It works perfectly so far .
For my understanding: What's the advantage of storing the objects externally to the registry vs on the registry?


There was just an "o" missing in your code. The following code works on of8 if anybody has the same issue as me:

Originally Posted by olesen

PtrList<IOdictionary> allMyProperties(solidRegions.size());

forAll(solidRegions, regioni)
{
    auto& mesh = solidRegions[regioni];
    allMyProperties.set
    (
        regioni,
        new IOdictionary
        (
             IOobject
             (
                  "myProperties",
                    mesh.time().constant(),
                    mesh,
                    IOobject::MUST_READ_IF_MODIFIED,
                    IOobject::NO_WRITE
             )
        )
    );
}

[olesen]

Originally Posted by F42

Thank you! It works perfectly so far .
For my understanding: What's the advantage of storing the objects externally to the registry vs on the registry?

The answer is "depend". If you have things that you will mostly or only be accessing via the objectRegistry lookups in various places, then storing to the registry probably fits well with your needs. Perhaps for your case you would like to access them both via the registries AND as a linear list, the external storage makes sense.


In some places, it is useful to check if a field exists (on the registry). If it doesn't, then create a local-scope autoPtr of the field and have it registered on the registry. When the autoPtr goes out of scope, its deletion will also remove the field from the registry. Gives a nice cleanup behaviour: leaves it on the registry if it already existed before, but also cleans up the local-scope one too.