On refinement of the porous body model for reactor hydrodynamics

The theory of filtration is commonly applied to calculate coolant flows in cores and heat exchangers as in anisotropic 'macroporous bodies' formed by rod and tube bundles. To describe the flow in tube space, use is made of the phenomenological motion equation where in an additional term with effective shift viscosity (by analogy with the Navies-Stokes equation) is entered in addition to the volumetric forces of resistance. The inertial terms of the motion equation playing a significant role in macroporous media with unsteady and non-uniform flows are usually written without considering the forces of the porous solid reaction to the liquid flow. It is shown that to take account of inertial forces, the macroscopically nonuniform and anisotropic porous media should be described by the scalar porosity field and the tensor field of effective dynamic density. In this case, the unsteady non-uniform filtration equation should contain additional terms accounting for both the macroheterogeneity of medium porosity and the anisotropy of effective dynamic density. By the example of the filtration flow of ideal liquid in simplified models of non-uniform anisotropic porous mediums, the physical meanings of the additional terms of the motion equation is illustrated, and of the hydrodynamic forces of interaction between the liquid flow and the porous solid are assumed. (author)