[Ahyar]

I have a simulation which has dispersed phase "air1" and "particle" with phaseProperties like below.

air1
{
type            pureIsothermalPhaseModel;

    diameterModel   velocityGroup;

    velocityGroupCoeffs
    {
        populationBalance    air3;

        shapeModel           spherical;

        sizeGroups
        (
            f1 {dSph  4e-3; value0.4;}
            f2 {dSph  5e-3; value0.2;}
            f3 {dSph  6e-3; value0.4;}

        );
    }

    residualAlpha   1e-8;
}

particle
{
type            pureIsothermalPhaseModel;

    diameterModel   velocityGroup;

    velocityGroupCoeffs
    {
        populationBalance    air4;

        shapeModel           spherical;

        sizeGroups
        (
            f4 {dSph  7e-3; value0.2;}
            f5 {dSph  8e-3; value0.6;}
            f6 {dSph  9e-3; value0.2;}
        );
    }

    residualAlpha   1e-8;
}

then i want to change the particle phase size groups into smaller one, so i changed its residualAlpha as well into this setting

particle
{
type            pureIsothermalPhaseModel;

    diameterModel   velocityGroup;

    velocityGroupCoeffs
    {
        populationBalance    air4;

        shapeModel           spherical;

        sizeGroups
        (
            f4 {dSph  7e-5; value0.2;}
            f5 {dSph  8e-5; value0.6;}
            f6 {dSph  9e-5; value0.2;}
        );
    }

    residualAlpha   1e-11;
}

now the simulation become divergent with this error





What should I replace/change to make the simulation run well? I've seen the titania synthesis in tutorial have smaller phase size and can be executed with no problem. What should I consider in setting the phaseProperties? thanks in advance