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Laminar flow in three-dimensional square-square expansions

Sousa, P.C. and Coelho, P.M. and Oliveira, Monica and Alves, M.A. (2011) Laminar flow in three-dimensional square-square expansions. Journal of Non-Newtonian Fluid Mechanics, 166 (17-18). pp. 1033-1048. ISSN 0377-0257

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Abstract

In this work we investigate the three-dimensional laminar flow of Newtonian and viscoelastic fluids through square–square expansions. The experimental results obtained in this simple geometry provide useful data for benchmarking purposes in complex three-dimensional flows. Visualizations of the flow patterns were performed using streak photography, the velocity field of the flow was measured in detail using particle image velocimetry and additionally, pressure drop measurements were carried out. The Newtonian fluid flow was investigated for the expansion ratios of 1:2.4, 1:4 and 1:8 and the experimental results were compared with numerical predictions. For all expansion ratios studied, a corner vortex is observed downstream of the expansion and an increase of the flow inertia leads to an enhancement of the vortex size. Good agreement is found between experimental and numerical results. The flow of the two non-Newtonian fluids was investigated experimentally for expansion ratios of 1:2.4, 1:4, 1:8 and 1:12, and compared with numerical simulations using the Oldroyd-B, FENE-MCR and sPTT constitutive equations. For both the Boger and shear-thinning viscoelastic fluids, a corner vortex appears downstream of the expansion, which decreases in size and strength when the elasticity of the flow is increased. For all fluids and expansion ratios studied, the recirculations that are formed downstream of the square–square expansion exhibit a three-dimensional structure evidenced by a helical flow, which is also predicted in the numerical simulations.

Item type: Article
ID code: 41368
Keywords: Viscoelastic fluid , Boger fluid, flow visualisation, PIV, 3D expansion flow, numerical simulations, Mechanical engineering and machinery, Mechanical Engineering, Computational Mechanics, Fluid Flow and Transfer Processes, Computer Vision and Pattern Recognition
Subjects: Technology > Mechanical engineering and machinery
Department: Faculty of Engineering > Mechanical and Aerospace Engineering
Technology and Innovation Centre > Advanced Engineering and Manufacturing
Depositing user: Pure Administrator
Date Deposited: 10 Oct 2012 08:59
Last modified: 26 Mar 2015 23:51
URI: http://strathprints.strath.ac.uk/id/eprint/41368

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