[Stefanie.S.W.]

Hello everyone,

I am using multiphaseEulerFoam and I would like to use other values than the default value of 0.07 N/m for sigma.

transportProperties
[...]
sigmas
(
(air water) 0.07
(air oil) 0.07
(oil water) 0.07
);

But whenever I change one or all values the simulation stops after the first written time step, I get error messages like:

multiphaseEulerFoam >>log.solve
#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::multiply(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4 void Foam::multiply<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam6/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam:perator*<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) in "/opt/openfoam6/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#6 Foam::multiphaseSystem::dragCoeffs() const at ??:?
#7 ? in "/opt/openfoam6/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
#8 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#9 ? in "/opt/openfoam6/platforms/linux64GccDPInt32Opt/bin/multiphaseEulerFoam"
Floating point exception (core dumped)

This specific error occurred when I changed all sigmas to 0.03. With the default values the simulation runs stable.

Does someone know why I can't change sigma? At some point I need to reduce the surface tension because I will use soapy water.

Thank you for your help!!

kind regards,
Stefanie


I am very uncertain which further information you need, hopefully I guessed right:

0 - alpha.air

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

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0; 

boundaryField
{
    mischzylinder
    {
        type            alphaContactAngle;
        thetaProperties ( ( oil air ) 90 0 0 0 ( water air ) 90 0 0 0 ( oil water ) 90 0 0 0 );
        value           uniform 1;
    }
    duese
    {
        type            alphaContactAngle;
        thetaProperties ( ( oil air ) 90 0 0 0 ( water air ) 90 0 0 0 ( oil water ) 90 0 0 0 );
        value           uniform 1;
    }
    zylinder
    {
        type            alphaContactAngle;
        thetaProperties ( ( oil air ) 90 0 0 0 ( water air ) 90 0 0 0 ( oil water ) 90 0 0 0 );
        value           uniform 0;
    }
    atmosphere
    {
        type            inletOutlet;
        inletValue      uniform 1;
        value           uniform 1;
    }
}

Alpha.oil and alpha.water are alike:

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

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0; 


boundaryField
{
    mischzylinder
    {
        type            zeroGradient;
    }
    duese
    {
        type            zeroGradient;
    }
    zylinder
    {
        type            zeroGradient;
    }
    atmosphere
    {
        type            inletOutlet;
        inletValue      uniform 0;
        value           uniform 0;
    }
}

I also posted a related question here:

multiphaseEulerFoam-transportProperties dict

[betterglobe]

Did you fix your problem?
The 0.07 N/m default value is probably from the fact that the surface tension of water is 0.0728N/m at 20degC.
I'm not sure about why 0.03 N/m caused a problem. If the IFT drops to zero, the two phases will become mixed soup. So maybe the low IFT is bad for convergence?