voidfractionModel_bigParticleVoidFraction command

Syntax:

Defined in couplingProperties dictionary.

voidfractionModel bigParticle;
bigParticleProps
{
    maxCellsPerParticle number1;
    alphaMin number2;
    scaleUpVol number3;
} 

• number1 = max number of cells covered by a partilce (search will fail when more than number1 cells are covered by the particle)
• number2 = mininmum limit for voidfraction
• number3 = diameter of the particle's representation is artificially increased according to number3 * Vparticle, volume remains unaltered!

Examples:

voidfractionModel bigParticle;
bigParticleProps
{
    maxCellsPerParticle 1000;
    alphaMin 0.10;
    scaleUpVol 5.0;
} 

Description:

The bigParticle voidFraction model is supposed to be used when a particle (or it's representation) is bigger than a CFD cell. The voidfraction field is set in those cell whose centres are inside the particle which results in a stairstep representation of the bodies within the mesh (i.e. voidfraction is either 1 (fluid) of zero (solid)). For archiving accurate results, approx. 8 cells per particle diameter are necessary.

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.

Restrictions: none.

Related commands:

voidfractionModel