Laminar flow past a sphere rotating in the transverse direction
- Authors
- Kim, Dongjoo
- Issue Date
- Feb-2009
- Publisher
- KOREAN SOC MECHANICAL ENGINEERS
- Keywords
- Sphere; Wake; Transverse rotation; Vortex shedding; Shear layer instability
- Citation
- JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY, v.23, no.2, pp 578 - 589
- Pages
- 12
- Journal Title
- JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
- Volume
- 23
- Number
- 2
- Start Page
- 578
- End Page
- 589
- URI
- https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/22279
- DOI
- 10.1007/s12206-008-1001-9
- ISSN
- 1738-494X
1976-3824
- Abstract
- Laminar flow past a sphere rotating in the transverse direction is numerically investigated in order to understand the effect of the rotation on the characteristics of flow over the sphere. Numerical simulations are performed at Re 100, 250 and 300, where the Reynolds number is based on the free-stream velocity and the sphere diameter. The rotational speeds considered are in the range of 0 <= omega* <= 1.2, where to omega* is the maximum velocity on the sphere surface normalized by the free-stream velocity. Without rotation, the flow past a sphere experiences steady axisymmetry, steady planar-symmetry, and unsteady planar-symmetry, respectively, at Re = 100, 250 and 300. With rotation, however, the flow becomes planar-symmetric for all the cases investigated, and the symmetry plane of flow is orthogonal to the rotational direction. Also, the rotation affects the flow unsteadiness, and its effect depends on the rotational speed and the Reynolds number. The flow is steady irrespective of the rotational speed at Re = 100, whereas at Re = 250 and 300 it undergoes a sequence of transitions between steady and unsteady flows with increasing omega*. As a result, the characteristics of vortex shedding and vortical structures in the wake are significantly modified by the rotation at Re = 250 and 300. For example, at Re = 300, vortex shedding occurs at low values of omega*, but it is completely suppressed at (omega* = 0.4 and 0.6. Interestingly, at omega* = 1 and 1.2, unsteady vortices are newly generated in the wake due to the shear layer instability. The critical rotational speed, at which the shear layer instability begins to occur, is shown to be higher at Re = 250 than at Re = 300.
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Collections - Department of Mechanical Engineering > 1. Journal Articles
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