Multiphase Fluid is a Fluid Mixture consisting of phases, each occupying its own space volume.
Each phase of the Multiphase Fluid is represented either by a pure substance or by a Fluid Mixture (see Multiphase Fluid vs Fluid Mixture).
This means that some Multiphase Fluids may consist of one pure substance and as such are not Fluid Mixtures.
Fluid Mixture is a sum of Fluid Components, which are pure chemical substances.
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