# Multiphase flow

Presently, PorousFlow provides several `Materials`

to model two-phase flow. However, all of the PorousFlow `Kernels`

are designed to be used with an arbitrary number of fluid phases, so that additional phases can be included in PorousFlow by simply creating new `Materials`

that provide properties for each phase.

Two-phase flow can be modelled using either formulations where porepressure of each phase are the nonlinear variables, or where porepressure and saturation of one phase are solved. These `Materials`

calculate the pressure and saturation of each fluid phases, as well as all derivatives with respect to the PorousFlow variables.

Two-phase flow with porepressure formulation

`PorousFlow2PhasePP`

Two-phase flow with porepressure - saturation formulation

`PorousFlow2PhasePS`