The Eulerian-Eulerian model is one of the two main multiphase models that has been implemented in Ansys CFX; the other is the Lagrangian Particle Tracking Model. For details, see Particle Transport Modeling.

Within the Eulerian-Eulerian model, certain interphase transfer terms used in momentum, heat, and other interphase transfer models, can be modeled using either the Particle Model, the Mixture Model or the Free Surface Model. In particular, the calculation of the interfacial area density, used for all inhomogeneous transfer models for a given fluid pair, is calculated according to one of these models. The model used for a particular pair of phases is set on the Fluid Pairs tab. The available options depend on the morphology of each phase of the pair (for example, continuous, dispersed, and so on), and on settings found on the Fluid Models tab (homogeneous options, free surface model option).