CFD Online Discussion Forums - Surface shear force in OpenFOAM-v1706

Hi!

I am working on a rivulet panel case and am trying to see the effect of surface shear force on a falling waterfilm due to crossflow. I have prepared the test case and had updated the reactingParcelFilmFoam solver according to my test-case.
Now, in OpenFOAM 2.1.1, there is a separate kinematic force - surfaceShearForce which can be enabled or disabled using the surfaceFilmProperties file in constant folder. In OpenFOAM versions 3.0.x and after (I tried both OpenFOAM 3.0.x and v1706), the surfaceShearForce is absent and instead of that, a member function has been included in the laminar turbulence model (src/regionModels/surfaceFilmModels/submodels/kinematic/filmTurbulenceModel/laminar/laminar.C)

Code:

 tmp<fvVectorMatrix> laminar::Su(volVectorField& U) const

  125 {

  126     // local reference to film model

  127     const kinematicSingleLayer& film =

  128         static_cast<const kinematicSingleLayer&>(filmModel_);

  129 

  130     // local references to film fields

  131     const volScalarField& mu = film.mu();

  132     const volVectorField& Uw = film.Uw();

  133     const volScalarField& delta = film.delta();

  134     const volVectorField& Up = film.UPrimary();

  135     const volScalarField& rhop = film.rhoPrimary();

  136 

  137     // employ simple coeff-based model

  138     volScalarField Cs("Cs", Cf_*rhop*mag(Up - U));

  139     volScalarField Cw("Cw", mu/(0.3333*(delta + film.deltaSmall())));

  140     Cw.min(5000.0);

  141 

  142     return

  143     (

  144        - fvm::Sp(Cs, U) + Cs*Up // surface contribution

  145        - fvm::Sp(Cw, U) + Cw*Uw // wall contribution

  146     );

  147 }

(Taken from: OpenFOAM v1706 source code)

If this is compared with the earlier surfaceShearForce code in OpenFOAM 2.1.1, it can be seen that the equations and the procedure is more or less same, except a few changes here and there (like in the case of Cw.min).

When I am running the case in OpenFOAM 2.1.1, I am getting a deviation in the film but when I am running the case in OpenFOAM 3.0.x and OpenFOAM -v1706, there is no such deviation.
I have also modified the laminar code to find out if the function is being called or not and it is being called.

Can anyone help me out in figuring why this difference is there?