[ziemowitzima]

Hi,
Are you sure that the term:
Foam::fvc::laplacian( D23*T , XV)
is correct?


shoudn't it be:


Foam::fvc::laplacian( D23*XV , T)


?

[Elham]

Originally Posted by ziemowitzima

Hi,
Are you sure that the term:
Foam::fvc::laplacian( D23*T , XV)
is correct?


shoudn't it be:


Foam::fvc::laplacian( D23*XV , T)


?

Hi,

Yes I am sure based of eq 2.2 "Fluid dynamics and transport of droplets and sprays", Sirignano 2nd edition.

[Elham]

Originally Posted by Elham

Dear Foamers,

In a multiphase fluid type, I have the following form of TEqn

    fvScalarMatrix TEqn
    (
          fvm::ddt(T)
        + fvm::div(phi,T)
        - Foam::fvm::laplacian( k/rhoCp , T)
    );


    TEqn.relax();

        solve
         (
            TEqn
            ==
            fvc::ddt(p)*(1/rhoCp)
            +Foam::fvc::laplacian( D23*T , XV)
         );

where XV is vapor mass fraction as following:

rhogp= (rho2*limitedAlpha2+rho3*limitedAlpha3)/(limitedAlpha2+limitedAlpha3);
XV= rho2/rhogp

with the above equation I got too unbounded alpha fields at very first step .If I manipulate TEqn as the following:

fvScalarMatrix TEqn
    (
          fvm::ddt(T)
        + fvm::div(phi,T)
        - Foam::fvm::laplacian( k/rhoCp , T)
        - Foam::fvm::laplacian( D23*T , XV)
    );


    TEqn.relax();

        solve
         (
            TEqn
            ==
            fvc::ddt(p)*(1/rhoCp)

         );

It will blow up at the first time step with the following error:

gradientInternalCoeficients cannot be called for a calculatedFvPatchField

I will apprciate any hint for fixing.

Cheers,

Elham

Ok. I could solve the above issue:

For the first equation, I changed it to

    fvScalarMatrix TEqn
    (
          fvm::ddt(rhoCpT)
        + fvm::div(rhoCpPhi,T)
        - Foam::fvm::laplacian( k , T)
    );


    TEqn.relax();

        solve
         (
            TEqn
            ==
            fvc::ddt(p)
            +Foam::fvc::laplacian( rho2*Cp2*D23*T , XV)
         );

and the temperature field did not get unbounded anymore. The reason is that rho is not constant as well as the Cp.
And as far as I've got Foam::fvc::laplacian( rho2*Cp2*D23*T , XV) in RHS I don't have gradientInternalCoeficients error.