IBVoidFractionConvex

Syntax

Defined in couplingProperties dictionary.

particleShapeType convex;
voidfractionModel IB;
IBProps
{
    maxCellsPerParticle  number;
    baseDirectory        word;
    particleSurfaces     wordList;
    surfaceCenterPoints  vectorList;
}

  • maxCellsPerParticle = maximum number of cells covered by a particle (search will fail when more than maxCellsPerParticle cells are covered by the particle)

  • baseDir = the base directory where to search for particle surface defintion files

  • particleSurfaces = a list of particle surface definitions, preferably the STL files also used for particle definition on the DEM side

    Note

    The order of this list must be identical to the order of particle templates in the DEM input script.

  • surfaceCenterPoints = list center points for particleSurfaces.

    Note

    This setting is not required, but if used it must be of the same size as particleSurfaces entry – AND in the same order.

Examples

particleShapeType convex;
voidfractionModel IB;
IBProps
{
    maxCellsPerParticle 4000;
    baseDirectory       "../DEM/data";
    particleSurfaces    ( "diamond1.stl" "diamond2.stl" );
}

Description

This variant of the IBVoidFraction model is specifically designed to work with convex particles in a resolved CFD-DEM context, i.e. when a convex particle is 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 will voidfraction values between 0 and 1.

Note

This model requires the usage of the particle surface definitions as on the DEM side. It is, however, not aware of any additional scalings that may be applied on the DEM side. Hence, particle surface definitions should be altered in a manner accessible to both the CFD and DEM, e.g. by using the surfaceTransformPoints utility to scale the input meshes.

The center of mass for the surfaces defined via particleSurfaces are internally calculatd by averaging the surface points weighted by the size of surface elemets they belong to. This procedure results in exact results for symmetric particles but may yield offsets for non-symmetric particles. You can mitigate this issue by specifying the center of mass manully using the surfaceCenterPoints setting.

Restrictions

Only for convex particles.