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Eddy structures in a transitional backward-facing step flow

Published online by Cambridge University Press:  24 September 2007

H. P. RANI
Affiliation:
Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, Taiwan
TONY W. H. SHEU
Affiliation:
Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, Taiwan
ERIC S. F. TSAI
Affiliation:
Department of Marine Engineering, National Taiwan Ocean University, Taiwan

Abstract

In the present study, flow simulation has been carried out in a backward-facing step channel defined by an expansion ratio of 2.02 and a spanwise aspect ratio of 8 to provide the physical insight into the longitudinal and spanwise flow motions and to identify the presence of Taylor–Görtler-like vortices. The Reynolds numbers have been taken as 1000 and 2000, which fall in the category of transitional flow. The present simulated results were validated against the experimental and numerical data and the comparison was found to be satisfactory. The simulated results show that the flow becomes unsteady and exhibits a three-dimensional nature with the Kelvin–Helmholtz instability oscillations and Taylor–Görtler-Like longitudinal vortices. The simulated data were analysed to give an in-depth knowledge of the complex interactions among the floor and roof eddies, and the spiralling spanwise flow motion. Destabilization of the present incompressible flow system, with the amplified Reynolds number due to the Kelvin–Helmholtz and Taylor–Görtler instabilities, is also highlighted. A movie is available with the online version of the paper.

Type
Papers
Copyright
Copyright © Cambridge University Press 2007

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References

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Rani et al. supplementary movie

Movie. Illustration of the spiralling particles for Re = 1000 using streamlines.  A, B, C, D denote the particle seeding points at (x/S, y/S, z/S) = (1, 1.975, 1), (1,1.9, 1), (0, 1, 4) and (1, 1, 4), respectively.

Download Rani et al. supplementary movie(Video)
Video 1.4 MB

Rani et al. supplementary movie

Movie. Illustration of the spiralling particles for Re = 1000 using streamlines.  A, B, C, D denote the particle seeding points at (x/S, y/S, z/S) = (1, 1.975, 1), (1,1.9, 1), (0, 1, 4) and (1, 1, 4), respectively.

Download Rani et al. supplementary movie(Video)
Video 1.8 MB