ABSTRACT
This chapter provides necessary background information and illustrations of two-phase flows in order to prepare for the derivation of the modeling equations, two-phase flow analyses, and real-world applications. It introduces a number of dispersed flow terms briefly. The chapter briefly describes the major two-phase flow systems and provides a few practical examples. Two terms that have been traditionally used for two-phase flow classifications are "flow pattern" and "flow regime." The rigorous two-phase flow modeling and analysis is one of the great (remaining) challenges in the classical sciences. There are two basic types of models, i.e., corpuscular/molecular models on the subcontinuum scale (kinetic theory) and continuum models on the micro/macroscale (continuum mechanics). The two-phase flow modeling, simulation, and design relies on system-specific data correlations, semiempirical equations, assumed probability density functions, or the use of random number generators, all somehow embedded in continuum mechanics laws and/or statistical mechanics concepts.
