[aee]

I am having difficulty getting a reactingParcelFilmFoam (OF2.3.1) past the point where particles are added to the film. The case is a bent pipe with hot vapor flowing through it (i.e., inlet, pipe, outlet), Cooler water is sprayed from an injector in the middle of the pipe. The goal is to see the path the film takes around the bend (and to see how much vaporizes from the spray and film).

The error is
#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 in "/lib/x86_64-linux-gnu/libc.so.6"
#3 log in "/lib/x86_64-linux-gnu/libm.so.6"
#4 Foam::H2O::mu(double, double) const at ??:?
#5 Foam::regionModels::surfaceFilmModels::liquidFilmT hermo::mu() const at ??:?
#6 Foam::regionModels::surfaceFilmModels::liquidVisco sity::correct(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
#7 Foam::regionModels::surfaceFilmModels::thermoSingl eLayer::solveEnergy() at ??:?
#8 Foam::regionModels::surfaceFilmModels::thermoSingl eLayer::evolveRegion() at ??:?
#9 Foam::regionModels::regionModel::evolve() at ??:?
#10
at ??:?
#11 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#12
at ??:?
Floating point exception (core dumped)

I suspect there is something wrong with the way I set up or solve the film, but I can't find the issue. The primary region flow develops and seems realistic. I have tried increasing the robustness of the fvschemes and fvSolutions, and trying BC and film properties from the tutorial cases. I also tried disabling non-critical models.
The only smoking gun is the temperature instability, with the film temperature rapidly dropping or climbing to extremes. Perhaps that means I don't have the heat transfer mapping or thermophysicals correct.

I can send the case files.
For what it is worth, I have a similar issue in OF3.0.1.

update: setting phaseChangeModel fron standardPhaseChange to none clears the error.

[aee]

Is there a repository for cases beyond the tutorials that come with openFoam? If I could find a case with similar conditions, I could see what discretization schemes, BC, etc are used.

I've tried numerous meshes, from 100k to 2M cells, and tried adapting the hotbox, splash panel and cylinder tutorials. None of those tutorials invoke phase change

Does anyone have a functioning rectingParcelFilmFoam case with phase change in the reactingCloud and from the surfaceFilm?

[aee]

After a dozen complete new builds of the model from various tutorial cases in 2.3.1 and 3.0.1, I have a running model converted from the splashpanel tutorial with the addition of an inlet, outlet, and new species, etc. The stumbling block has always been the heat transfer modeling. For the case mentioned above, it crashed the model as soon as a parcel was added to the film. For the current model, it was runaway temperatures of the gas phase until I added a limitTemperature option in the fvOptions file as discussed in the thread
http://www.cfd-online.com/Forums/ope...ng-v3-0-a.html

I recommend that thread for anyone experiencing similar issues. I consider my problem solved for now - at least until I learn what I might have done better with the heat transfer settings other than just limit the temperature.

[aee]

I have a simulation running with reactingPrcelFilmFoam OF3.0.1) in which the film Max Courant number is 0.96 while the bulk fluid has a Max Co No of 0.27 at a time step of 1.3e-05. The bulk fluid update takes 3 pimple loops over 400k cells, while the film is solved very quickly.

I also have an interFoam simulation running that does 2 alpha sub-loops (nAlphaSubCycles 2) for each flow loop, which helps with the simulation time. That lead me to wonder, Is there a way to do multiple iterations of a surface film for each iteration of the bulk fluid to speed up a reactingParcelFilmFoam simulation?

[CjjJoy]

So in the reactingParcelFilmFoam solver, the wall film region is solvered in Euler method or Lagrange nethod?

[neilk]

Sir,

I am trying to run a thin film simulation on a bifurcating channel. The channel has a thin fluid lining on it and I want to see how the film evaporates when hot air is passed though it. Have you been able to get satisfactory results for you film evaporating? If so how have you modeled the surfaceFilm?

Also, I keep getting the error for unfeasible temperature in the bifurcating channel as the temperature reaches 0 Kelvin after a point. Could you please help me out?

Thank you

Nilay

[neilk]

Sir,
I am trying to run the surface film simulation for bifurcating flow with film thickness of 1e-5m. The film temperature is 300K and the airflow temperature is 350K. I was expecting a decrease in the deltaf value but after 1 sec the deltaf value becomes 1e-3, 100 times its original magnitude? Any ideas as to why this might be happening?

Thank you

Nilay

[aee]

My temperature issue was with the bulk vapor. Once I limited that, the film stayed under that too. However, the simulation was of a spray of cold fluid into a hot vapor stream. The evaporation of the droplets and of the film seems reasonable, but I did not verify it. The intent was to show a pattern of flow for the film.

0 K is obviously nonphysical, but I don't know what might have caused that. You might compare your case files against the hotbox tutorial. In your case, if the film is water, surface tension may pull it to smaller patches of film. 1mm seems odd though, from a 10 micrometer start..

[neilk]

Hello.
I am still trying to run a evaporation study. I have generated a surface film on the bottom patch of the cube and want to check the continuous evaporation if air with 50% relative humidity flows over it at the system temperature of 20 degree C.
I have attached the H20, T, Tf boundary conditions below. Could you please tell me where I am going wrong? Because with these conditions I get condensation rather than evaporation.

Thank you

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      H2O;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0.001;

boundaryField
{
    INLET
    {
        type            fixedValue;
		value			uniform 0.001;
    }
    OUTLET
    {
        type            zeroGradient;
    }
    
    WALL
    {
        type            zeroGradient;
    }

    region0_to_wallFilmRegion_wallFilmFaces
    {
        type            fixedValue;
		value			uniform 0.001;
    }
}

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 293;

boundaryField
{
    INLET
    {
        type            fixedValue;
       value           uniform 293;
    }

    region0_to_wallFilmRegion_wallFilmFaces
    {
        type            fixedValue;
       value           uniform 293;
    }

    WALL
    {
        type            fixedValue;
       value           uniform 293;
    }
    
    OUTLET
    {
        type            zeroGradient;
    }
    
}

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0/region0_to_"(region0_to.*)"Region_masterRegion";
    object      Tf;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform  293;

boundaryField
{
    // cyclic boundaries between film patches
	Inlet
    {
        type            zeroGradient;
    }

    // top film surface
    Outlet
    {
        type            zeroGradient;
    }
	
	WALL
    {
        type            fixedValue;
       value           uniform 293;
    }

    // mapped boundaries
    wallFilmFaces_top
    {
	   type            fixedValue;
       value           uniform 293;
    }

    // floor sides
    region0_to_wallFilmRegion_wallFilmFaces
    {
	   type            fixedValue;
       value           uniform 293;
    }
}

[aee]

try setting T on all boundaries other than inlet to zero gradient. Tf too.
(i.e., initial internal field and inlet at 293 K.)
Haven't looked at this for a while. Is this the same problem you were working on a few months ago?

[neilk]

Yes. But back then my inlet temperatures were also high. I recently found a paper where they experimentally documented the evaporation at ambient temperature, so I've been trying to simulate and validate my results with that experiment. I had a couple of doubts regarding this evaporation model.

1. The length scale defined in standardPhaseChangeCoeffs in surfaceFilmProperties. How to select this length scale as it directly affects the mass transfer coefficient according to standardPhaseChang.C?

2. In standardPhaseChang.C the mass fraction at the interface is calculated based on the pressure in the cell and the vapor pressure. So would keeping a calculated boundary condition at the mapped wall, i.e. at region0_to_wallFilmRegion_wallFilmFaces be better for H2O field?

Thank you