Picture of satellite hovering above Earth

Open Access research exploring new frontiers in aerospace engineering...

Strathprints makes available Open Access scholarly outputs by the Department of Mechanical & Aerospace Engineering at Strathclyde, which includes an emphasis on air and space research. The Advanced Space Concepts Laboratory (ASCL), the Future Air-Space Transportation Technology Laboratory (FASTTlab) and the Intelligent Computational Engineering Laboratory (ICElab) specialise in this work.

The ASCL undertakes frontier research on visionary space systems, delivering radically new approaches to space systems engineering. Meanwhile, FASTTlab seeks to revolutionise the global air-space transportation systems and infrastructure. ICElab develops advanced research on artificial and computational intelligence techniques with particular focus on optimisation, optimal control, uncertainty-based multidisciplinary design optimisation and machine learning applied to the design and control of complex engineering systems.

Learn more and explore the Open Access research by ASCL, FASTTlab and ICElab. Or, explore all of Strathclyde's Open Access research...

Effect of the contraction ratio upon viscoelastic fluid flow in three-dimensional square-square contractions

Sousa, P.C. and Pinho, F.T. and Oliveira, Monica and Alves, M.A. (2011) Effect of the contraction ratio upon viscoelastic fluid flow in three-dimensional square-square contractions. Chemical Engineering Science, 66 (5). pp. 998-1009. ISSN 0009-2509

[img] PDF
Oliveira_M_Effect_of_the_contraction_ratio_upon_viscoelastic_fluid_flow_in_three_dimensional_square_to_square_contractions_Mar_2011.pdf
Final Published Version

Download (2MB)

Abstract

In this work we investigate the laminar flow through square–square sudden contractions with various contraction ratios (CR¼2.4, 4,8and12), using a Newtonian fluid and a shear-thinning viscoelastic fluid. Visualizations of the flow patterns were carried out using streakline photography and detailed velocity field measurements were performed using particle image velocimetry. The experimental results are compared with numerical predictions obtained using a finite-volume method. For the Newtonian fluid, a corner vortex is found upstream of the contraction and increasing flow inertia leads to a reduction of the vortex size. Good agreement is observed between experiments and numerical simulations. For the shear-thinning fluid flow a corner vortex is also observed upstream of the contraction independently of the contraction ratio. Increasing the elasticity of the flow, while still maintaining low inertia flow conditions, leads to a strong increase of the vortex size, until an elastic instability sets in and the flow becomes time-dependent at DeE200, 300, 70 and 450 for CR¼2.4, 4, 8 and 12, respectively. At low contraction ratios, viscoelasticity brings out an anomalous divergent flow upstream of the contraction. For both fluids studied the flow presents a complex three-dimensional helical vortex structure which is well predicted by numerical simulations. However, for the viscoelastic fluid flow the maximum Deborah number achieved in the numerical simulations is about one order of magnitude lower than the critical Deborah number for the onset of the elastic instability found in the experiments.