Plugs in Viscometric Flows of Simple Semi-liquids

This concept provides a general framework which includes almost all previously proposed mathematical models for Non-Newtonian fluids as special cases and also, of course, the classical theory of Navier-Stokes fluids. It turned out that only this general concept, and no special mathematical models, were needed to analyze the behavior of simple liquids (incompressible simple fluids) in viscometric flows. This analysis was presented, in detail, in Chapter E of [NLFT], published first in 1965, and in [VF], published in 1966. The theory of simple liquids could not describe the mechanical behavior of many of the materials studied by rheologists, for example the phenomena described by what they call “Bingham materials”. Also, it did not include Ericksen’s Theory of Anisotropic Fluids as a special case. Aware of these shortcomings, W.N. introduced, in 1972, what he called the New Theory of Simple Materials ([N2]). It is based primarily on the following ideas: