bigParticleVoidFraction

Syntax

Defined in couplingProperties dictionary.

voidfractionModel bigParticle;
bigParticleProps
{
    maxCellsPerParticle  label;
    alphaMin             scalar;
    voidfractionFieldName word
    weight               scalar;
    porosity             scalar;
    procBoundaryCorrection Switch;
}

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

Note

The search will fail when more cells than the indicated number are covered by the particle.
alphaMin = minimum limit for voidfraction (default: 0.1)
voidfractionFieldName = name of the finite volume voidfraction field (default: “voidfraction”)
weight = scaling of the particle volume to account for porosity or agglomerations. (default: 1)
porosity = diameter of the particle’s representation is artificially increased according to porosity * Vparticle, volume remains unaltered! (default: 1)
procBoundaryCorrection = allow for correction at processor boundaries. This requires the use of engineIB and vice versa. (default: false)

Examples

voidfractionModel bigParticle;
bigParticleProps
{
    maxCellsPerParticle 1000;
    alphaMin 0.10;
    voidfractionFieldName voidfraction;
    weight 1.;
    porosity 5.0;
}

Description

The bigParticle 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 cells 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) or zero (solid)). To yield accurate results, approx. 8 cells per particle diameter are necessary.

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

The particle volume occupied in the CFD domain can be adjusted by the parameter weight, using $V_\mathrm{p} = d^3 \frac{\pi}{6} \mathit{weight}$ .

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

Restrictions

None.