Introduction. General Principles of Description of Two-Phase Systems

Abstract

The general concept of the two-phase systems and their classification is presented. Basic methods of two-phase flows description are discussed: method of detailed description, unit cell models, single continuum models, models of multispeed medium. The main problems and limitations of existing approaches to the development of mathematical models are shown. It turned out that the correct choice of the coordinate system in many cases can simplify the description of the two-phase systems. The examples describing the typical two-phase systems behaviour in ‘laboratory coordinate system’ and in ‘native coordinate system’ are presented. The detailed study of the problem of the proper assignment of the ‘coupling conditions’, which are 'inner' boundary conditions written on the boundaries of coexisting phases is carried out. The general equations governing the coupling conditions were derived, and then reduced for a broad set of individual cases of practical and scientific interest. The basic approach to the determination of the intensity of nonequilibrium phase transitions in two-phase flows is presented. Finally, the structure of the book is described and a brief content of the individual chapters is presented.