[elowfoam]

Hello Everyone,

I am running a simulation using reactingParcelFoam and am encountering a crash after the surface film begins to form. The simulation consists of an injector at the entrance of a pipe which sprays droplets into the pipe. The film should form on the pipe wall and an object inside the pipe body before exiting the pipe at the outlet. The droplets are dispersed in air which is flowing through the pipe and calculated with RANS. The issue is that the film temperature goes out of control as well as the film velocity. I tried turning I am not using a heat transfer model and so I'm not sure why the temperature is going too high.

Any ideas on what could be causing this issue?? Thank you

Here is the log file right before the crash:

Surface film: thermoSingleLayer
    added mass         = 1.457017136e-05
    current mass       = 2.427114927e-06
    min/max(mag(U))    = 1.265353865e-10, 1157.435938
    min/max(delta)     = 0, 0.000422582137
    coverage           = 0.0002297272491
    injected mass      = 0
      - patch: region0_to_wallFilmRegion_wallFilmFaces: 1.248587004e-05
    transferred mass      = 0
      - patch: region0_to_wallFilmRegion_wallFilmFaces: 0
    min/mean/max(T)    = -2.368582975e+225, 1.219816906e+292, 4.591152679e+296
    mass phase change  = 0
    vapourisation rate = 0

Here is the Uf and Tf files for the BCs of the film taken from the 0/ directory:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0/wallFilmRegion";
    object      Uf;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    wallFilmFaces_top
    {
        type            slip;
    }

    region0_to_wallFilmRegion_wallFilmFaces
    {
        type    noSlip;
    }

    outlet
    {
        type            zeroGradient;
    }

    inlet
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
}

Tf:

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

dimensions      [0 0 0 1 0 0 0];

internalField   uniform  300;

boundaryField
{
    wallFilmFaces_top
    {
        type            fixedValue;
        value           uniform 300.0;
    }

    region0_to_wallFilmRegion_wallFilmFaces
    {
        type            fixedValue;
        value           uniform 300.0;
    }

    outlet
    {
                type            fixedValue;
        value           uniform 300.0;
    }

    inlet
    {
        //type            zeroGradient;
        type            fixedValue;
        value           uniform 300.0;
    }
}

Here is the surfaceFilmProperties file:

FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      surfaceFilmProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

surfaceFilmModel thermoSingleLayer;

region          wallFilmRegion;

active          true;

thermoSingleLayerCoeffs
{
    filmThermoModel liquid;

    liquidCoeffs
    {
        useReferenceValues  no;
        liquid      H2O;
    }

    filmViscosityModel liquid;

    deltaWet    1e-4;

    hydrophilic no;

    turbulence  laminar;
    laminarCoeffs
    {
        Cf          0.005;
    }

    forces
    (
        thermocapillary
    );


    phaseChangeModel none;
    radiationModel none;

    upperSurfaceModels
    {
        heatTransferModel constant;
        constantCoeffs
        {
            c0                1e-8;
        }
    }

    lowerSurfaceModels
    {
        heatTransferModel constant;
        constantCoeffs
        {
            c0                1e-8;
        }
    }


    injectionModels
    (
        curvatureSeparation
    );

    curvatureSeparationCoeffs
    {
        definedPatchRadii
        (
            ("(region0_to_wallFilmRegion_wallFilmFaces)" 0)
        );
     }
}

[stamufa]

Were you able to solve this? Do the temp and velocity go out of bounds as soon as soon as particles enter the film region? This may then have something to do with how the film region is set up. When I perform the extrudeMesh in another direction as what the default is, I get unbounded velocity and delta too.

[Antus]

Hi, by anychance did you solve this problem, I am trying to solve a similar case and I cannot manage to make the film work. I have some particles injected (patchInjection, at the inlet) and when they collide to the waal they are not absorbed in the film...



At first I also had the same diverging problem of yours with temperature diverging as soon as the particles were injected and I solved it with a refined mesh and a better look-up at my boundary conditions.