[zbtlfd]

Hello everyone,

hopefully a more experienced OpenFOAM/C++ developer can answer my question regarding the dynamic_cast operation used in the thermophysicalModels library, and specifically in the chemistryModel class, which extends the basicChemistryModel class. In the constructor in chemistryModel.C, the dynamic_cast operation is used to downcast from a basicMultiComponentMixture to a reactingMixture:

template<class CompType, class ThermoType>
Foam::chemistryModel<CompType, ThermoType>::chemistryModel
(
    const fvMesh& mesh,
    const word& phaseName
)
:
    CompType(mesh, phaseName),
    ODESystem(),
    Y_(this->thermo().composition().Y()),
    reactions_
    (
        dynamic_cast<const reactingMixture<ThermoType>&>(this->thermo())
    ),
    specieThermo_
    (
        dynamic_cast<const reactingMixture<ThermoType>&>
            (this->thermo()).speciesData()
    ),

    nSpecie_(Y_.size()),
    nReaction_(reactions_.size()),
    Treact_(CompType::template lookupOrDefault<scalar>("Treact", 0.0)),
    RR_(nSpecie_)

However, this->thermo() actually points to either the class rhoReactionThermo or psiReactionThermo, which in itself contains the method composition(), which returns a reference to basicMultiComponentMixture. Therefore from my understanding of this method, the data members, specifically the ones using dynamic_cast,should be initialized like this in the constructor:

template<class CompType, class ThermoType>
Foam::chemistryModel<CompType, ThermoType>::chemistryModel
(
    const fvMesh& mesh,
    const word& phaseName
)
:
    CompType(mesh, phaseName),
    ODESystem(),
    Y_(this->thermo().composition().Y()),
    reactions_
    (
        dynamic_cast<const reactingMixture<ThermoType>&>(this->thermo().composition())
    ),
    specieThermo_
    (
        dynamic_cast<const reactingMixture<ThermoType>&>
            (this->thermo().composition()).speciesData()
    ),

    nSpecie_(Y_.size()),
    nReaction_(reactions_.size()),
    Treact_(CompType::template lookupOrDefault<scalar>("Treact", 0.0)),
    RR_(nSpecie_)

Obviously the original version works as well, however I don't understand why. I stumbled over this, when I tried to extend the basicMultiComponentMixture class with a couple of new member variables for my model extension. The code still compiled, but trying to access specieThermo_ fails because it is empty. It seems like I could fix it with my updated version.
Could somebody provide more insights or explanations here, if my understanding of the operation is correct and why it was implemented the way it is now in OpenFOAM?

Thank you very much!
Lukas

[zbtlfd]

Actually this->thermo() does not return a reference to rhoReactionThermo or psiReactionThermo, since they're just the abstract base classes, but rather heThermo, which seems to be inheriting from rho/psiReactionThermo.

Still, it seems much more logical to directly cast from the returned reference (basicMultiComponentMixture) of the composition() method to the reactingMixture instead of casting from the heThermo object to reactingMixture.