Laminar flow in three-dimensional square-square expansions

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Sousa, PC (Author) FEUP; Coelho, PM (Author) FEUP; Oliveira, MSN (Author) Other; Alves, MA (Author) FEUP

Journal

Title: Journal of Non-Newtonian Fluid Mechanics

Vol. 166

Pages: 1033-1048

ISSN: 0377-0257

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 9 Citations

ISI Web of Science

Scopus - 14 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-002-MHA

DOI: 10.1016/j.jnnfm.2011.06.002

Abstract (EN): 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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16