Strathprints logo
Strathprints Home | Open Access | Browse | Search | User area | Copyright | Help | Library Home | SUPrimo

Three-dimensional flow of Newtonian and Boger fluids in square-square contractions

Sousa, P.C. and Coelho, P.M. and Oliveira, Monica and Alves, M.A. (2009) Three-dimensional flow of Newtonian and Boger fluids in square-square contractions. Journal of Non-Newtonian Fluid Mechanics, 160 (2-3). pp. 122-139. ISSN 0377-0257

[img]
Preview
PDF
Oliveira_M_Three_dimensional_flow_of_Newtonian_and_Boger_fluids_in_square_square_contractions_Aug_2009.pdf - Published Version

Download (4MB) | Preview

Abstract

The flow of a Newtonian fluid and a Boger fluid through sudden square–square contractions was investigated experimentally aiming to characterize the flow and provide quantitative data for benchmarking in a complex three-dimensional flow. Visualizations of the flow patterns were undertaken using streakline photography, detailed velocity field measurementswere conducted using particle image velocimetry (PIV) and pressure drop measurements were performed in various geometries with different contraction ratios. For the Newtonian fluid, the experimental results are compared with numerical simulations performed using a finite volume method, and excellent agreement is found for the range of Reynolds number tested (Re2 ≤23). For the viscoelastic case, recirculations are still present upstream of the contraction but we also observe other complex flow patterns that are dependent on contraction ratio (CR) and Deborah number (De2) for the range of conditions studied: CR = 2.4, 4, 8, 12 and De2 ≤150. For low contraction ratios strong divergent flow is observed upstream of the contraction, whereas for high contraction ratios there is no upstream divergent flow, except in the vicinity of the re-entrant corner where a localized a typical divergent flow is observed. For all contraction ratios studied, at sufficiently high Deborah numbers, strong elastic vortex enhancement upstream of the contraction is observed, which leads to the onset of a periodic complex flow at higher flow rates. The vortices observed under steady flow are not closed, and fluid elasticity was found to modify the flow direction within the recirculations as compared to that found for Newtonian fluids. The entry pressure drop, quantified using a Couette correction, was found to increase with the Deborah number for the higher contraction ratios.

Item type: Article
ID code: 41375
Keywords: viscoelastic fluid, PIV, visualisation, 3D contraction flow, Boger fluid, Mechanical engineering and machinery, Mechanical Engineering, Fluid Flow and Transfer Processes, Computational Mechanics, Computer Vision and Pattern Recognition
Subjects: Technology > Mechanical engineering and machinery
Department: Faculty of Engineering > Mechanical and Aerospace Engineering
Depositing user: Pure Administrator
Date Deposited: 11 Oct 2012 10:59
Last modified: 23 Jul 2015 15:16
URI: http://strathprints.strath.ac.uk/id/eprint/41375

Actions (login required)

View Item View Item