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The influence of fluid elasticity on wall effects for creeping sphere motion in cylindrical tubes
Author(s) -
Chhabra R. P.,
Uhlherr P. H. T.
Publication year - 1988
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450660124
Subject(s) - weissenberg number , elasticity (physics) , spheres , shear thinning , newtonian fluid , rheology , viscosity , mechanics , physics , materials science , optics , thermodynamics , astronomy
Experimental results are presented of wall effect for the slow motion of spheres in elastic, constant‐viscosity liquids. The results are correlated in terms of diameter ratio for d/D < 0.3, and Weissenberg number We < 5. Weissenberg number is defined as We = 2θ V m / d , with θ the Maxwellian relaxation time (θ = N 1 /2τγ). The wall effect is found to be adequately described by Newtonian expressions for small Weissenberg number, We < 0.01. For larger values of the Weissenberg number, We > 0.2, virtually no wall effect is discernible; the small effect observed is correlated by the wall factor expression The wall effect observed is ascribed to the influence of fluid elasticity alone, since all the fluids used were elastic to a greater or lesser extent, but showed no shear thinning.\documentclass{article}\pagestyle{empty}\begin{document}$$ f = 1 - 0.17d/D $$\end{document}