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Simulation of unsteady three-dimensional flow around a square cylinder at moderate Reynolds numbers

Sohankar, Ahmad ; Norberg, Christoffer LU and Davidson, Lars (1999) In Physics of Fluids 11(2). p.288-306
Abstract
Direct numerical simulations of two-dimensional (2D) and 3-D unsteady flow around a square cylinder for moderate Reynolds numbers (Re=150–500) are performed, employing an implicit fractional step method finite-volume code with second-order accuracy in space and time. The simulations, which are carried out with a blockage ratio of 5.6%, indicate a transition from 2-D to 3-D shedding flow between Re=150 and Re=200. Both spanwise instability modes, A and B, are present in the wake transitional process, similar to the flow around a circular cylinder. However, seemingly in contrast to a circular cylinder, the transitional flow around a square cylinder exhibits a phenomenon of distinct low-frequency force pulsations (Re=200–300). For 3-D... (More)
Direct numerical simulations of two-dimensional (2D) and 3-D unsteady flow around a square cylinder for moderate Reynolds numbers (Re=150–500) are performed, employing an implicit fractional step method finite-volume code with second-order accuracy in space and time. The simulations, which are carried out with a blockage ratio of 5.6%, indicate a transition from 2-D to 3-D shedding flow between Re=150 and Re=200. Both spanwise instability modes, A and B, are present in the wake transitional process, similar to the flow around a circular cylinder. However, seemingly in contrast to a circular cylinder, the transitional flow around a square cylinder exhibits a phenomenon of distinct low-frequency force pulsations (Re=200–300). For 3-D simulations, the Strouhal number and the mean drag coefficient are in general agreement with existing experiments. Between Re=300 and 500, an increase in the spanwise coupling of fluctuating forces is indicated. The influence of the spanwise aspect ratio using periodic boundary conditions, a finer grid, and a finer time step is also investigated.
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type
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publication status
published
subject
in
Physics of Fluids
volume
11
issue
2
pages
288 - 306
publisher
American Institute of Physics (AIP)
external identifiers
  • scopus:0000928634
ISSN
1070-6631
DOI
10.1063/1.869879
language
English
LU publication?
yes
id
7ad5c9f4-d6aa-4d79-8aac-a213144ec32f
date added to LUP
2022-10-13 17:14:33
date last changed
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@article{7ad5c9f4-d6aa-4d79-8aac-a213144ec32f,
  abstract     = {{Direct numerical simulations of two-dimensional (2D) and 3-D unsteady flow around a square cylinder for moderate Reynolds numbers (Re=150–500) are performed, employing an implicit fractional step method finite-volume code with second-order accuracy in space and time. The simulations, which are carried out with a blockage ratio of 5.6%, indicate a transition from 2-D to 3-D shedding flow between Re=150 and Re=200. Both spanwise instability modes, A and B, are present in the wake transitional process, similar to the flow around a circular cylinder. However, seemingly in contrast to a circular cylinder, the transitional flow around a square cylinder exhibits a phenomenon of distinct low-frequency force pulsations (Re=200–300). For 3-D simulations, the Strouhal number and the mean drag coefficient are in general agreement with existing experiments. Between Re=300 and 500, an increase in the spanwise coupling of fluctuating forces is indicated. The influence of the spanwise aspect ratio using periodic boundary conditions, a finer grid, and a finer time step is also investigated.<br/>REFERENCES}},
  author       = {{Sohankar, Ahmad and Norberg, Christoffer and Davidson, Lars}},
  issn         = {{1070-6631}},
  language     = {{eng}},
  number       = {{2}},
  pages        = {{288--306}},
  publisher    = {{American Institute of Physics (AIP)}},
  series       = {{Physics of Fluids}},
  title        = {{Simulation of unsteady three-dimensional flow around a square cylinder at moderate Reynolds numbers}},
  url          = {{http://dx.doi.org/10.1063/1.869879}},
  doi          = {{10.1063/1.869879}},
  volume       = {{11}},
  year         = {{1999}},
}