The Multiphase Flow in Porous Media interface () combines the Darcy’s Law interface with the Phase Transport in Porous Media interface to model the flow and transport of multiple immiscible phases in a porous medium.

When a predefined Multiphase Flow in Porous Media interface is added from the Porous Media and Subsurface Flow branch () of the Model Wizard or Add Physics window, Phase Transport and Darcy’s Law interfaces are added to the Model Builder. In addition, the Multiphysics node is added, which automatically includes the Multiphase Flow in Porous Media multiphysics coupling.

The Phase Transport in Porous Media interface is used to simulate the transport of immiscible multiple species in a porous medium and solves for their averaged volume fractions (also called saturations). The interfaces between the different phases are not tracked explicitly, although microscopic interfacial effects are taken into account in the macroscopic equations through the capillary pressure functions.

The Darcy’s Law interface is used to simulate fluid flow through interstices in a porous medium. It can be used to model low-velocity flows in media where the permeability and porosity are very small, and for which the pressure gradient is the major driving force and the flow is mostly influenced by the frictional resistance within the pores.

When physics interfaces are added using the predefined couplings, for example Multiphase Flow in Porous Media, specific settings are included with the physics interfaces and the coupling features.

For example, if single Phase Transport in Porous Media and Darcy’s Law interfaces are added, an empty Multiphysics node appears in the model tree. You can choose from the available coupling features but the settings in the constituent interfaces are not modified.