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

• Tipo: Artigo em Revista Científica Internacional
• Data: 2009

Autores

Sousa, PC (Autor) Outra; Coelho, PM (Autor) FEUP; Oliveira, MSN (Autor) Outra; Alves, MA (Autor) FEUP

Revista

Título: Journal of Non-Newtonian Fluid Mechanics

Vol. 160 Nº 1

Páginas: 122-139

ISSN: 0377-0257

Editora: Elsevier

Indexação

ISI Web of Knowledge - 24 Citações

ISI Web of Science

Scopus - 29 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia mecânica

Outras Informações

ID Authenticus: P-003-H55

DOI: 10.1016/j.jnnfm.2009.03.009

Abstract (EN): 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 streak-line photography, detailed velocity field measurements were 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 (Re(2) <= 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 (De(2)) for the range of conditions studied: CR = 2.4, 4, 8, 12 and De(2) <= 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 atypical 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.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 18