[andresbh]

Hi
I am trying to solve this equation in openfoam.

dS_dt + div(vect(U)*f(S))=q

where f(S) is a known equation dependent of S. S cannot be explicitly extracted from f(S).

up to now if I implement the equation as stated above I get an error concerning calculatedFvPatchField.


Has anybody had similar problems?

Thanks

Andres

[alberto]

A bit vague :-)

You should give some more detail on how the equation was implemented, and be specific with the error message.

Best,

[andresbh]

Hi Alberto,

I hope that the problem declaration this time is more illustrating.

Implementation:

The initial values of

volScalarField S
volVectorField U

are read from the case directory 0 and

dimensionedScalar const1
dimensionedScalar const2

from the constant directory.

The implementation reads

    volScalarField X = (S-const1)/(const2);
    f = pow(X,2)/(2*pow(X,2)-2*X-1);

    phi = linearInterpolate(U) & mesh.Sf();
    fvScalarMatrix SEqn
        (
            por*fvm::ddt(S) +
            fvm::div(phi,f) ==
            q
        );
        solve(SEqn);

Error: 

--> FOAM FATAL ERROR: 

    valueInternalCoeffs cannot be called for a calculatedFvPatchField
    on patch fixedWalls of field f in file "/home/i/andres/Simulations/FOAM/darcy2/0/f"
    You are probably trying to solve for a field with a default boundary condition.

    From function calculatedFvPatchField<Type>::valueInternalCoeffs(const tmp<scalarField>&) const
    in file fields/fvPatchFields/basic/calculated/calculatedFvPatchField.C at line 145.

I am no very sure what this means. Do I need to create my own boundary condition to fulfill this? or can I define my equation in another way ?

Thanks

Andres

[niklas]

try to replace
fvm::div(phi,f)
with
fvc::div(phi,f)

You cant solve implicitly for both f and S, they arent really the same fields are they?