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Abstract

The phenomenon of physical wake flow is complex and remains relatively unknown, especially for the relationship between the span-wise motions of separated shear layers and low frequency variations embedded in the vortex shedding process of upstream disturbances. In this study experiments were executed by situating a mesh grid and controlling cylinder upstream. Results showed that the integral time scale of the span-wise motions for a separated shear layer was close to that of the low frequency variations for an upstream disturbance. This evidence supports the idea that span-wise motions of a separated shear layer and the low frequency variations should appear at same time in the vortex shedding process. In addition, the visibility of the low frequency variations obtained was fixed at about 10% of flow energy regardless of flow disturbance from upstream. Finally, a physical representation regarding the span-wise oscillation of the shear layer and the low frequency variations in the vortex shedding process was constructed and appeared in chaotic behavior. These findings will be useful to further the understanding of the wake flow model.

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