Dynamics of vortical structures in cylinder/wall interaction with moderate gap ratio

The interaction between the wake of a transverse circular cylinder and the underlying flat-plate boundary layer with a moderate gap ratio G/D=1.0 is investigated using both hydrogen-bubble-based and PIV-based visualization techniques. The spanwise rollers in the cylinder wake are found to be capable...

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Bibliographic Details
Published in:Journal of fluids and structures 2013-11, Vol.43, p.100-109
Main Authors: He, G.S., Pan, C., Wang, J.J.
Format: Article
Language:English
Subjects:
Cylinders
Fluid dynamics
Fluid flow
Hydrogen bubble flow visualization
PIV measurement
Rollers
Secondary vortex
Three dimensional
Vortices
Wake/boundary layer interaction
Wakes
Walls
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Summary:The interaction between the wake of a transverse circular cylinder and the underlying flat-plate boundary layer with a moderate gap ratio G/D=1.0 is investigated using both hydrogen-bubble-based and PIV-based visualization techniques. The spanwise rollers in the cylinder wake are found to be capable of inducing secondary vortices in the near-wall region. The mutual induction from the counter-clockwise rollers, which are closer to the wall, plays a primary role, so that these secondary vortices present linear lift-up motion at first. Their subsequent evolution dominantly determines the characteristics of the wake/boundary-layer interaction. Two different vortex interaction scenarios are observed: the secondary vortices can be either entrained into the rollers or pushed down towards the wall. This leads to a rapid three-dimensional destabilization process, through which streamwise vortices are generated. And it is suggested that these streamwise vortices are the dominant structures to promote the following boundary layer transition.
ISSN:0889-9746
1095-8622
DOI:10.1016/j.jfluidstructs.2013.09.005