ABSTRACT
This chapter presents the porous media procedure in which the region of interest is divided into a network of volumes or lumped regions, each of which will be characterized by volume-averaged parameters. The porous media approach is a practical method of analyzing both the reactor core and the steam generator situations. This approach has been widely used for analysis of large regions containing only fluid (continuum) and for flows in regions with immersed solids. Here the principles of this method are illustrated for the situation of the behavior of a flow field in which an array of heated rods is immersed. Two following approaches to the development of the relevant porous media equations are identified and demonstrated:
Integration of the differential, fluid conservation equations over a volume containing the distributed solids.
Direct application of the conservation principles to a volume containing the distributed solids.
Mastery of both approaches enhances the ability to survey the existing literature.
The conservation equations that are derived in this chapter are instantaneous, volume-averaged relations applicable to single-phase conditions. The time averaging of the single-phase relations is done in Chapter 6 as part of the procedure of specializing these results to a subchannel-sized control volume.
