For flows in which a dilute phase is dispersed in a continuous phase, you should use the Fluid Dependent turbulence option with the model for the continuous fluid and the Dispersed Phase Zero Equation option for the dispersed phase. At wall boundaries, the dispersed phase should also use the Free Slip Wall option for Mass And Momentum. This type of flow can occur in bubble columns.

The turbulent Prandtl number for an algebraic model should be unity, except for large heavy particles, in which case it should be greater than unity.

For flows in which the phases tend to separate (for example, inhomogeneous free surface flows and oil-water separators), the homogeneous turbulence model is recommended.