On extensibility effects in the cross-slot flow bifurcation

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Gerardo N Rocha (Author) Other; Robert J Poole (Author) Other; Manuel A Alves (Author) FEUP; Paulo J Oliveira (Author) Other

Journal

Title: Journal of Non-Newtonian Fluid Mechanics

Vol. 156 No. 3

Pages: 58-69

ISSN: 0377-0257

Publisher: Elsevier

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ISI Web of Knowledge - 40 Citations

ISI Web of Science

Scopus - 54 Citations

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Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-003-R2A

DOI: 10.1016/j.jnnfm.2008.06.008

Abstract (EN): The flow of finite-extensibility models in a two-dimensional planar cross-slot geometry is studied numerically, using a finite-volume method, with a view to quantifying the influences of the level of extensibility, concentration parameter, and sharpness of corners, on the occurrence of the bifurcated flow pattern that is known to exist above a critical Deborah number. The work reported here extends previous studies, in which the viscoelastic flow of upper-convected Maxwell (UCM) and Oldroyd-B fluids (i.e. infinitely extensionable models) in a cross-slot geometry was shown to go through a supercritical instability at a critical value of the Deborah number, by providing further numerical data with controlled accuracy. We map the effects of the L-2 parameter in two different closures of the finite extendable non-linear elastic (FENE) model (the FENE-CR and FENE-P models), for a channel-intersecting geometry having sharp. "slightly" and "markedly" rounded corners. The results show the phenomenon to be largely controlled by the extensional properties of the constitutive model, with the critical Deborah number for bifurcation tending to be reduced as extensibility increases. In contrast, rounding of the corners exhibits only a marginal influence on the triggering mechanism leading to the pitchfork bifurcation. which seems essentially to be restricted to the central region in the vicinity of the stagnation point.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12