
The tracking of the interface(s) between the phases is accomplished by the solution of a continuity equation for the volume fraction of one (or more) of the phases. For the th phase, this equation has the following form:
By default, the source term on the righthand side of Equation 22.21 is zero, but you can specify a constant or userdefined mass source for each phase. See Section 22.5 for more information on the modeling of mass transfer in FLUENT's general multiphase models.
The volume fraction equation will not be solved for the primary phase; the primaryphase volume fraction will be computed based on the following constraint:
(22.22) 