voidfractionModel_dividedVoidFraction command

Syntax:

Defined in couplingProperties dictionary.

voidfractionModel divided;
dividedProps
{
    alphaMin number1;
    interpolation;
    weight number2;
    porosity number3;
} 

• number1 = minimum limit for voidfraction
• interpolation = flag to interpolate voidfraction to particle positions (normally off)
• number2 = (optional) scaling of the particle volume to account for porosity or agglomerations.
• number3 = (optional) diameter of the particle's representation is artificially increased according to number2 * Vparticle, volume remains unaltered!

Examples:

voidfractionModel divided;
dividedProps
{
    alphaMin 0.2;
} 

Description:

The divided 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 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. Appropriate names for these fields have to be specified in the sub-dictionaries voidFracFieldNamesPrev and voidFracFieldNamesNext in the couplingProperties dictionary.

Restrictions: none.

Related commands:

voidfractionModel