weightedNeigbhorsVoidFraction

Syntax

Defined in couplingProperties dictionary.

voidfractionModel weightedNeighbor;
weightedNeighborProps
{
    alphaMin number1;
    scaleUpVol number2;
    interpolation;
    weight number3;
    porosity number4;
}

  • number1 = minimum limit for voidfraction

  • number2 = diameter of the particle’s representation is artificially increased according to number2 * Vparticle, volume remains unaltered!

  • interpolation = flag to interpolate voidfraction to particle positions (normally off)

  • number3 = (optional) scaling of the particle volume to account for porosity or agglomerations.

  • number4 = (optional) diameter of the particle’s representation is artificially increased according to number2 * Vparticle, volume remains unaltered!

Examples

voidfractionModel weightedNeighbor;
weightedNeighborProps
{
    alphaMin 0.2;
    weight 1.;
    porosity 2.;
}

Description

The weightedNeighbor voidFraction model is supposed to be used when a particle (or its representation) is in the size range of a CFD cell. Satellite points are used to divide the particle’s volume to the touched cells. The particle volume is divided among these touching cells, weighted by the inverse of the particle center-to-cell center distance. This model works very similar to the divided model, which uses a different weighting.

The region of influence of a particle can be increased artificially by “porosity”, 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 Vparticle=dsphere^3*pi/6*weight.

In the basic implementation of solvers, the void fraction is calculated based on all particles. Depending on the solver used, the void fraction calculation is also performed for a certain type of particles. The void fraction calculation is based on a three-step approach (reset, set and interpolate), i.e., the void fraction is time interpolated from a previous and a next void fraction field.

Restrictions

Not well tested for periodic boundaries, as well as processor boundaries.