Interaction Area Density

The interaction area density specifies the interfacial area available for momentum, heat, and mass transfer between each pair of phases in an interaction.

Heat and mass transfer models use the interaction area density directly.

For Eulerian multiphase flow, drag models use one quarter of the interfacial area as an estimate of the projected area. Any correction factors, such as for non-spherical particle shapes or particle crowding, are assumed to be covered in correlations for the drag, heat, and mass transfer coefficients. There are two built-in models for interaction area density in Simcenter STAR-CCM+: spherical particle and symmetric.

Spherical Particle Interaction Area Density

This is based on the surface area of a spherical particle, and is not applicable at high particle volume fractions. For this model, the interaction area density $a_{cd}$ between a continuous phase (subscript c) and a dispersed phase (subscript d) is:

$$a_{cd}=\frac{6{\alpha }_d}{l_{cd}}$$

(1923)

where ${\alpha }_d$ is the volume fraction for the dispersed phase in the interacting phase pair and $l_{cd}$ is the interaction length scale for the pair.

Symmetric Particle Interaction Area Density

The availability of the continuous phase modifies the symmetric particle interaction area density, and so can be used for a wide range of volume fractions:

$$a_{cd}=\frac{6{\alpha }_c{\alpha }_d}{l_{cd}}$$

(1924)

where:

• ${\alpha }_d$ is the volume fraction for the dispersed phase in the interacting phase pair

• ${\alpha }_c$ is the volume fraction for the continuous phase in the pair

• $l_{cd}$ is the interaction length scale for the pair.