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Characterisation of inelastic power‐law fluids using falling sphere data
Author(s) -
Uhlherr P. H. T.,
Le T. N.,
Tiu C.
Publication year - 1976
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.5450540603
Subject(s) - weissenberg number , power law , falling (accident) , spheres , drag , mechanics , physics , shear rate , newtonian fluid , flow (mathematics) , stokes flow , thermodynamics , rheology , mathematics , medicine , statistics , environmental health , astronomy
Two simple methods are presented for the characterization of inelastic power law fluids from falling sphere data. The methods involve the application of shear rate or shear stress correction factors which have been derived theoretically using Slattery's solution for creeping flow about spheres. Flow curves obtained using these methods are in excellent agreement with those measured on a Weissenberg rheogoniometer for 0.83 ≤ n ≤ 1.0. The experimentally determined drag coefficients are found to be in good agreement with the predictions of Slattery's creeping flow first approximation solution. The wall correction factors of Faxen and Francis appear to be valid for inelastic non‐Newtonian fluids up to a diameter ratio of at least 0.08.