Additional Variables can exist in all fluids or only a limited number of fluids in a multiphase simulation. In addition, both homogeneous and phase-specific Additional Variables are supported. Phase-specific Additional Variables may be transferred between two phases provided that, for both phases, a transport equation is solved for the Additional Variable and a kinematic diffusivity has been set. It is also possible to have interphase transfer from a transported Additional Variable into an algebraic Additional Variable (that is, the algebraic Additional Variable acts like an Additional Variable source or sink).