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Surface-Mounted Bluff Bodies of Finite Height |
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David Sumner, Ph.D., P.Eng., Professor Department of Mechanical Engineering, University of Saskatchewan |
| Overview |
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Surface-mounted bluff bodies of finite height immersed in cross-flow are commonly found in many engineering applications, including the flow past buildings, chimneys, cooling towers, and oil storage tanks. The boundary layer developed on the ground, the interaction of this boundary layer with the body, and the flow over the body’s free end, have pronounced effects on flow separation, Kármán vortex shedding, the aerodynamic forces, and the development of the wake. The classic example of this type of three-dimensional (3-D) bluff body is the finite circular cylinder, where the flow behaviour is strongly influenced by the cylinder aspect ratio, the thickness of the boundary layer on the ground plane, and the Reynolds number. However, due to the complexity of the flow, the finite cylinder has not been as extensively investigated, and its physical behaviour is relatively poorly understood, compared to the “infinite” (2-D) circular cylinder, despite the many practical applications, including problems of flow-induced vibrations. |
| Finite Circular Cylinder |
| My research into the flow around a finite circular cylinder mounted normal to a ground plane has led to some new insight into the wake structure and vortex shedding. The focus has been on small- and medium-aspect-ratio circular cylinders where the cylinder is partially immersed in a flat-plate boundary layer. An experimental approach was followed, using a seven-hole pressure probe, thermal anemometry, and force measurements. Of particular interest was the effect of cylinder aspect ratio on Kármán vortex shedding, the mean drag force coefficient, the time-averaged wake velocity and streamwise vorticity fields, and the turbulence structure in the cylinder wake. |
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Last updated October 13, 2009 |