## 14.7. Multiphase Flows

The following topics will be discussed:

- Homogeneous Model

- Inhomogeneous Model

- N-Phase Flow

### Homogeneous Model

For two-phase flow using the homogeneous model, expect memory requirements to increase by a factor of 1.5 and CPU time to increase by a factor of 1.7 over the same single-phase simulation. Enabling free surface does not significantly alter CPU or memory requirements.

### Inhomogeneous Model

For two-phase flow using the particle or mixture models, expect memory requirements to increase by a factor of 2.15 and CPU time to increase by a factor of 2.25. Enabling free surface does not significantly alter CPU or memory requirements.

### N-Phase Flow

As the number of fluids increase, expect memory and CPU requirements to increase approximately linearly for small N. Tetrahedral meshes have more of a linear increase than hexahedral meshes. The table below gives approximate memory increase factors for up to 5 phases when compared to the same single-phase simulation on a hexahedral mesh.

# of Phases | Memory Increases
--- | ---
(Hex Mesh) | (Tet Mesh)
1 | 1 | 1.80
2 | 2.15 | 3.40
3 | 3.50 | 5.70
4 | 5.15 | 8.05
5 | 7.00 | 10.60

Expect the CPU factor to be slightly less than the corresponding memory factors, but the trend is the same.

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