Multifluid Theory of a Plasma

Abstract

In the previous chapters, we considered mainly two-phase flows in which two different kinds of fluid mix together to form a mixture for the whole flow field. Sometimes, we have to consider the mixture of more than two kinds and we call the resultant flow as multiphase flow if this fluid consists of liquid and/or gas and/or fluidized solid particles. Multiphase flow is sometimes called multicomponents flow if those fluids are in the same phase but of different kinds. For instance, we consider the mixture of several kinds of gases. A plasma may be considered as a mixture of N species which consists of ions, electrons and neutral particles. These ions and neutral particles in a plasma are usually gas particles. But in some occasions, these ions and neutral particles may be solid particles or aerosols. Hence, in a general sense, the plasma flow is a multiphase flow. From a macroscopic point of view, a complete description of the flow field of a plasma should consist of the fluid dynamic variables of all species, i.e., velocity vectors, pressure, density and temperature as well as the specific intensity of radiation of all species, and the electromagnetic fields. Such an analysis is known as multifluid theory of radiation magnetogasdynamics [12]. The multi-fluid theory of a plasma consisting of neutral and charged gas particles has been extensively studied [2, 13]. With some modifications, this classical multifluid theory of gases may be extended for the case of multiphase flow. The multifluid theory of a mixture of gases has been studied both from the microscopic [2] and the macroscopic point of view [13]. Hence, we are going to discuss both as well as the relations between these two approaches so that we may have better understanding on the fundamental equations of the multiphase flow.