Reiner-Philippoff equation

The entire flow curve for pseudoplastic behaviour can often be fit using the Reiner-Philippoff equation ... 

The literature [5] lists numerous different, material laws. It therefore should be noted at this point that the more coefficients a material law has, the more complicated it is to measure them, and the more difficult it is to incorporate them into equations of momentum and motion. For the calculation of an extruder, such equations yield differential-equation systems with elaborate flow laws that defy analytical resolution. Consequently, the measured flow curve should be approximated with the aid of a relatively uncomplicated material law that still adequately describes the extrusion compound. Several of the approaches used in plastics/rubber/pharma-ceutical technology include [6] power approach after Ostwald/de Waele and formulations according to Carreau, Miistedt, Casson, Herschel/ Bulk-ley, Bingham and Reiner/Philippoff... 

A rather complete survey of the entire field of viscometry, including the mathematical relationships applicable to various types of instruments, has been made by Philippoff (P4). The problem of slip at the walls of rotational viscometers has been discussed by Mooney (M15) and Reiner (R4). Mori and Ototake (M17) presented the equations for calculation of the physical constants of Bingham-plastic materials from the relationship between an applied force and the rate of elongation of a rod of such a fluid. ... 

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