Low-Reynolds-number flow around a square cylinder at incidence: study of blockage, onset of vortex shedding and outlet boundary condition
✍ Scribed by A. Sohankar; C. Norberg; L. Davidson
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 387 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0271-2091
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✦ Synopsis
Calculations of unsteady 2D ¯ow around a square cylinder at incidence a 0 45 are presented. The Reynolds numbers are low (Re 45±200) so that the ¯ow is presumably laminar. A von Ka Ârma Ân vortex sheet is predicted behind the cylinders with a periodicity which agrees well with experiments. An incompressible SIMPLEC code is used with a non-staggered grid arrangement. A third-order QUICK scheme is used for the convective terms. The time discretization is implicit and a second-order Crank±Nicolson scheme is employed. At the outlet of the computational domain a convective Sommerfeld boundary condition is compared with a traditional Neumann condition. The convective boundary condition is shown to be more effective in reducing the CPU time, reducing the upstream in¯uence of the outlet and thus reducing the necessary downstream extent of the domain. A study of the effects of spatial resolution and blockage is also provided. The onset of vortex shedding is investigated by using the Stuart±Landau equation at various angles of incidence and for a solid blockage of 5%. A number of quantities such as Strouhal number and drag, lift and moment coef®cients are calculated.