An investigation of the wake structure of a circular cylinder using a computer aided flow visualization. I - Generation and dissipation of the vorticity
Abstract
The flow fields near the surface and downstream of a 400-mm-long 30-mm-diameter Al cylinder exposed to a 20-m/s air flow (corresponding to Reynolds number 37,000) in the 500 x 500-mm working section of a return-circuit wind tunnel are characterized experimentally using the computer-assisted-flow-visualization techniques described by Davies (1976) and Owen and Johnson (1980). A novel conditional-sampling phase-averaging technique is used to process the signals, which are subject to both amplitude and frequency modulation. The results are presented graphically and discussed in detail, considering the total circulation discharged from the surface per shedding cycle, the phase-averaged streamlines and vorticity fields of the wake, the convection speed, and the inner vortex structure. It is found that less than 40 percent of the discharged circulation is accounted for by the near-wake vortex, the rest being lost in the base region due to vorticity cancelling.
- Publication:
-
JSME International Journal Series B
- Pub Date:
- May 1986
- Bibcode:
- 1986JSMEB..29.1446T
- Keywords:
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- Circular Cylinders;
- Flow Geometry;
- Near Wakes;
- Numerical Flow Visualization;
- Vortex Shedding;
- Aerodynamic Drag;
- Bluff Bodies;
- Boundary Layer Flow;
- Computer Graphics;
- Reynolds Number;
- Velocity Distribution;
- Fluid Mechanics and Heat Transfer