voidfractionModel_IBVoidFraction command


Defined in couplingProperties dictionary.

voidfractionModel IB;
    maxCellsPerParticle number1;
    alphaMin number2;
    scaleUpVol number3;
    checkPeriodicCells ;
  • number1 = maximum number of cells covered by a particle (search will fail when more than number1 cells are covered by the particle)
  • number2 = minimum limit for voidfraction
  • number3 = diameter of the particle’s representation is artificially increased according to number3 * Vparticle, volume remains unaltered!
  • checkPeriodicCells = (optional, default false) flag for considering the minimal distance to all periodic images of this particle


voidfractionModel IB;
    maxCellsPerParticle 1000;
    alphaMin 0.10;
    scaleUpVol 5.0;


The IB voidFraction model is supposed to be used when a particle (or its representation) is bigger than a CFD cell. The voidfraction field is set in those cell whose centres are inside the particle. The model is specially designed for cfdemSolverIB and creates a smooth transition of the voidfraction at the particle surface. Cells which are only partially covered by solid are marked by voidfraction values between 0 and 1 respectively.

The region of influence of a particle can be increased artificially by “scaleUpVol”, which blows up the particles, but keeps their volume (for voidfraction calculation) constant.

Code of this sub-model contributed by Alice Hager, JKU.