IBVoidFraction

Syntax

Defined in couplingProperties dictionary.

voidfractionModel IB;
IBProps
{
        maxCellsPerParticle  label;
        alphaMin             scalar;
        voidfractionFieldName word
        writeRefinementIndicator Switch;
        refinementCutoffRadius scalar;
        minCellsPerParticle  label;
        refinementRegionFilename "filename";
}

  • maxCellsPerParticle = maximum number of cells covered by a particle (default: 1000)

    Note

    The search will fail if more than maxCellsPerParticle cells are covered by the particle!

  • alphaMin = minimum limit for voidfraction (default: 0)

  • voidfractionFieldName = name of the finite volume voidfraction field (default: “voidfraction”)

  • writeRefinementIndicator = Switch to activate the output of refinement indicator field named refIndicator. This field can be used to control mesh refinement in dynamicMeshDict and uses the following values to indicate if further refinement is required or not:

    • refIndicator = 200: further refinement required

    • refIndicator =  10: no further refinement required

    • refIndicator =   0: cell not covered by paticle –> unrefine

    (default: false)

  • refinementCutoffRadius = refIndicator is only written for particles with a radius >= refinementCutoffRadius. Only those particles can be handled in resolved way by the hybridVoidFraction model. (default: 0)

  • minCellsPerParticle = desired number of cells per particle. (default: maxCellsPerParticle / 2)

  • refinementRegionFilename = triangulated surface filename in STL format which contains one or more solid regions where refinement will happen. (default: undefined)

    Note

    The minCellsPerParticle and refinementRegionFilename settings are only valid in combination with writeRefinementIndicator true.

Examples

voidfractionModel IB;
IBProps
{
    maxCellsPerParticle 1000;
    alphaMin 0.10;
    voidfractionFieldName voidfraction;
}

Description

The IB voidFraction model is supposed to be used in resolved CFD-DEM setups, i.e. when a particle (or its representation) is substantially larger than a CFD cell.

The voidfraction field is set in those cells whose centres are inside the particle. The model is specifically designed for cfdemSolverIB and other IB solvers and creates a smooth transition of the voidfraction at the particle surface. Cells which are only partially covered by the particle are marked by voidfraction values between 0 and 1 respectively.

When setting writeRefinementIndicator true the model calculates the refinement indicator field by comparing the cell volume with the particle volume divided by minCellsPerParticle. This means that small cells will be refined less than larger cells and a somewhat equal cell size within the particle should be obtained. If no refinementRegionFilename is given, the whole domain will be refined, otherwise only the (solid) region(s) defined in the STL file (which must be located in the “CFD/constant/triSurface” directory) will be refined.

The code of this model was contributed by Alice Hager, JKU.

Restrictions

None.