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Numerical evaluation of a method for determining extensional viscosity of fluids using contraction flow analysis
Author(s) -
Davies A. R.,
Farah I. M.,
Rides M.,
Thomas K.
Publication year - 1993
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19930680105
Subject(s) - extensional viscosity , extensional definition , rheology , rheometry , pressure drop , constitutive equation , mechanics , viscosity , drop (telecommunication) , materials science , capillary action , thermodynamics , mathematics , geology , physics , shear viscosity , computer science , finite element method , paleontology , telecommunications , tectonics
We report an evaluation of the use of Binding's method (Ref 11) for determining extensional viscosity values from capillary die rheometry entrance pressure drop data. A constitutive relation defining the fluid's rheological behaviour is first postulated, from which the pressure drop in a contraction region is calculated by numerical simulation for a range of flow rates. Extensional viscosity estimates are then made from the simulated pressure drop data using Binding's method, and these estimates are compared with the exact extensional viscosity determined from the constitutive relation. A highly accurate augmented spectral method is used to perform the numerical simulation. The Binding estimates obtained are good for certain types of fluid, but poor for others. A simple empirical correction of the Binding method, however, is found to give good agreement in all the cases studied.