## 7.3. Eulerian-Eulerian Multiphase Versus Particle Transport

A multiphase flow containing dispersed particles may be modeled using either the particle transport (`Lagrangian Particle Tracking`) model or the `Eulerian-Eulerian` multiphase model. Some advantages and disadvantages of the `Eulerian-Eulerian` multiphase model are given below to aid in the choice of model. The equivalent section for the particle transport model is available in Particle Transport Versus Eulerian-Eulerian Multiphase.

Table 7.1: Eulerian-Eulerian Multiphase vs. Particle Transport

Advantages of Eulerian-Eulerian Multiphase | Disadvantages of Eulerian-Eulerian Multiphase
--- | ---
Complete global information for the particle phase is available | Expensive if many sets of equations are used; that is, if there are many particle sizes. However, the homogeneous MUSIG model is an `Eulerian-Eulerian` model that uses a single velocity field for multiple size groups.
Applicable for wide range of volume fractions | Knowledge of the diffusion coefficients is incomplete
Relatively cheap for one additional set of equations | Difficult to get accuracy over a range of particle sizes for combustive flows
Turbulence is included automatically | When there is phase change, the particle diameter must be user-specified rather than calculated automatically by the model. This can decrease accuracy. (The droplet condensation model is an exception.)

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