CFD Online Discussion Forums - build my own multi-region solver : pb with flux continuity

Hi !

I am currently trying to develop my own multi-region solver. For sake of simplicity, let's say I have two regions, a "solid" and a "fluid". I want to solve heat transfers in both regions, with continuity and flux continuity at the solid/fluid interface.

Code:

fvScalarMatrix TsEqn

(

    fvm::laplacian(DTs,Ts)

);

TsEqn.solve();



fvScalarMatrix TfEqn

(

    fvm::laplacian(DTf,Tf)

);

TfEqn.solve();

Basically, I defined a solid_to_fluid and a fluid_to_solid patch to patch interpolation

Code:



    patchToPatchInterpolation solid_to_fluid

    (

        solidMesh.boundaryMesh()[labelSolid],

        fluidMesh.boundaryMesh()[labelFluid]

    );





    patchToPatchInterpolation fluid_to_solid

    (

        fluidMesh.boundaryMesh()[labelFluid],

        solidMesh.boundaryMesh()[labelSolid]

    

    );

I apply successfully the value of Ts at the solid/fluid interface as a boundary condition for Tf :

Code:

    scalarField &TsP = Ts.boundaryField()[labelSolid];

    scalarField &TfP = Tf.boundaryField()[labelFluid];



    TfP = solid_to_fluid.faceInterpolate(TsP);

This part is ok.

My problem concern the flux continuity at the region interface. I want to apply the flux continuity imposing the solid temperature gradient at the interface with

Code:

    vectorField n = fluidMesh.boundary()[labelFluid].nf();



    volVectorField gradTf = DTf/DTs*fvc::grad(Tf);



    scalarField nGradTf = n & gradTf.boundaryField()[labelFluid] ;



    fixedGradientFvPatchScalarField& gradTsPatch=refCast<fixedGradientFvPatchScalarField>(Ts.boundaryField()[labelSolid]); 

    scalarField& gradTsField =  gradTsPatch.gradient();



    gradTsField = p2_to_p1.faceInterpolate(nGradTf);

However it fails to have good result, and I can't have flux continuity. Is someone have an idea to solve my problem ?

best regards,
Cyp