CFD Online Discussion Forums - Heat capacity of species

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Heat capacity of species

Dears,

I am going to implement a new model for calculating viscosity that needs to heat capacity of each species. The new solver is based on reactingFoam.

Is it possible to get heat capacity of all species in all computational cells of the domain?

I used the following with no success.

Code:

volScalarField cpi = composition.Cp(i,T);

where
i is the label of species and

Code:

basicMultiComponentMixture& composition = thermo.composition();

Thank you in advance,

Hossein

If you look at the documentation, the return value for the Cp is a single scalar, and the inputs are single scalars as well. To get Cp for a single field like this you will need to go through each species, and each cell, and calculate the mass weighted Cp.

Or you can use the cp function from the thermo class that does this already:

Code:

volScalarField cp = thermo.cp();

Thanks Marco,

How can I go through each species? I'm using OF2.1.x. In the documentation of basicMultiComponentMixture.H we read:

Code:

//- Heat capacity at constant pressure [J/(kg K)]

            virtual scalar Cp(const label specieI, const scalar T) const = 0;

But I can not reach and I encounter the following error:

Code:

YEqn.H:53:52: error: no matching function for call to  ‘Foam::basicMultiComponentMixture::Cp(Foam::label&, const  volScalarField&)’

YEqn.H:53:52: note: candidate is:

In file  included from  /home/mohammad/OpenFOAM/OpenFOAM-2.1.x/src/thermophysicalModels/reactionThermo/lnInclude/hsCombustionThermo.H:39:0,

                  from  /home/mohammad/OpenFOAM/OpenFOAM-2.1.x/src/thermophysicalModels/chemistryModel/lnInclude/psiChemistryModel.H:43,

                 from /home/mohammad/OpenFOAM/OpenFOAM-2.1.x/src/combustionModels/lnInclude/psiChemistryCombustionModel.H:43,

                 from myReactingFoam.C:35:

/home/mohammad/OpenFOAM/OpenFOAM-2.1.x/src/thermophysicalModels/reactionThermo/lnInclude/basicMultiComponentMixture.H:134:28:  note: virtual Foam::scalar  Foam::basicMultiComponentMixture::Cp(Foam::label, Foam::scalar) const

/home/mohammad/OpenFOAM/OpenFOAM-2.1.x/src/thermophysicalModels/reactionThermo/lnInclude/basicMultiComponentMixture.H:134:28:  note:   no known conversion for argument 2 from ‘const volScalarField  {aka const Foam::GeometricField<double, Foam::fvPatchField,  Foam::volMesh>}’ to ‘Foam::scalar {aka double}’

Because it needs scalar instead of volScalarField. Is there any way to extract Cp value from a volScalarField value (temperature)?
Your second suggestion gives the heat capacity of each cell but not each species. Also,

Code:

thermo.cp();

leads to

Code:

class Foam::hsCombustionThermo’ has no member named ‘cp’

cp shold be replaced by Cp

I used the following to get the species' heat capacities:
In createFields:

Code:

PtrList<volScalarField>& cpi = Y;

forAll( cpi, rowI){

      cpi[rowI].setSize(mesh.cells().size(), 0);

}

and in YEqn.H:

Code:

    forAll(T, cellI)

    {   

        forAll(Y, specieI)

        {

            cpi[specieI][cellI] = composition.Cp(specieI,T[cellI]);

        }

    }

Any Comments?