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Elongational flow in a two‐dimensional channel geometry
Author(s) -
Khomami B.,
McHugh A. J.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070330506
Subject(s) - geometry , mechanics , newtonian fluid , open channel flow , flow (mathematics) , duct (anatomy) , stokes flow , extensional definition , fluid dynamics , physics , streamlines, streaklines, and pathlines , channel (broadcasting) , classical mechanics , mathematics , geology , engineering , medicine , paleontology , pathology , electrical engineering , tectonics
An analysis has been carried out of the two‐dimensional elongational flow in an impinging channel geometry having either straight or converging wall downstream ducts. Numerical solutions for Stokes flow were obtained using a nonorthogonal transformation of variables which converts the system to a square grid geometry. Calculations show that a strong extensional flow exists from the point of channel impingement to a distance downstream approximately D/4 where D is the channel depth at the impingement point. Extensional gradients and total fluid strains also increase when the downstream duct is convergent as opposed to being straight. An experimental analysis of the velocity field in the former geometry demonstrates that, under slow flow conditions, the kinematics of a Newtonian and a highly non‐Newtonian fluid become indistinguishable in the downstream region. The latter observation is shown to be consistent with second‐order fluid theory and the Giesekus‐Tanner Theorem.