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Entrance flows of polymeric materials: Pressure drop and flow patterns
Author(s) -
Boles R. L.,
Davis H. L.,
Bogue D. C.
Publication year - 1970
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.760100106
Subject(s) - pressure drop , mechanics , materials science , viscoelasticity , newtonian fluid , flow (mathematics) , inertial frame of reference , reynolds number , open channel flow , flow birefringence , drop (telecommunication) , classical mechanics , polymer , composite material , physics , mechanical engineering , turbulence , engineering
Flow at the entrance of a tube or channel is of interest in many polymer processes. Except for mathematical treatments at high Reynolds numbers and in creeping Newtonian flow, one must turn to empirical correlating equations and qualitative observations. These are discussed in two parts, one on pressure drop and the other on flow patterns. The discussion of pressure drop is largely a review, dealing with inertial, viscous, and elastic contributions to the pressure drop in tapered and sharp‐edged entrances; also presented are new data for a viscoelastic polymer solution in tapered cone entrances. In the section on flow patterns, stress birefringent data for a very elastic solution flowing into a channel entrance show an unusual effect: stress discontinuities, not unlike “shock waves,” upstream and downstream of the entrances. This is in contrast to Newtonian and less elastic materials in which the stress patterns change gradually between the developed flow region and the entrance region.