Balance equations for a single-phase material

Abstract

This chapter extends the discussion of Chapter 2 by accounting for changes that may occur in the conserved quantities that characterize a single-phase material. This is necessary, of course, since a materials processing operation is typically conducted in order to change the condition of a material--its form and/or its composition-when passing from starting materials to product. The set of conserved quantities identified in Chapter 2 provides a sufficiently accurate description of a material at a particular position and a given time, but cannot account for spatial or temporal variations in the value of those quantities. It is thus the purpose of this chapter to describe the manner in which the conserved quantities that were discussed in the previous chapter may change (or, more precisely, be caused to change) (i) with respect to time, at a given position in the material, as well as (ii) with respect to position in the material, at a given instant.