ABSTRACT
There is a bewildering variety of notation in the literature relative to two-phase flow, and this chapter attempts to use a notation that is consistent with the following definitions for solid–liquid, solid–gas, and liquid–gas systems. The conveying of solids by a fluid in a pipe involves a wide range of flow conditions and phase distributions, depending on the density, viscosity, and velocity of the fluid; the density, size, shape, and concentration of the solid particles; or the orientation of the pipe. Either a liquid or a gas can be used as the carrier fluid, depending on the size and properties of the particles. However, there are important differences between hydraulic and pneumatic transport. If the solid particles are very small, and/or not greatly denser than the fluid, and/or the flow is highly turbulent, the mixture may behave as a uniform suspension with essentially continuous properties with no slip between the two phases.
