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Steady bi‐directional drag flow of non‐newtonian liquids in shallow channels
Author(s) -
Lindt J. Thomas
Publication year - 2000
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11206
Subject(s) - drag , carreau fluid , plastics extrusion , mechanics , flow (mathematics) , materials science , newtonian fluid , extrusion , non newtonian fluid , polymer , thermodynamics , mechanical engineering , composite material , physics , engineering
This paper reexamines the analytical framework for the steady, fully developed two‐dimensional flow in shallow channels, typical of screw extruders, and provides comprehensive solution sets for the Carreau‐Yasuda and the Ostwald‐deWaele model fluids. An application example for polymethylmethacrylate (PMMA) is included to compare the relative merits of the two models under specific extrusion conditions. The Ostwald‐deWaele model, standard in engineering practice, can produce gross misrepresentations of the flow in extruder channels. Particularly, when dealing with highly shear‐sensitive polymers, n < 0.3, or polymers with extended Newtonian plateau, ∧ ∼ 1, the Carreau‐Yasuda model becomes preferable. The inclusion of the Carreau model does not necessarily add to the complexity of the analysis.