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|Title:||Tilting of vortex rings in cross-flow|
|Citation:||Proceedings of the 21st Australasian Fluid Mechanics Conference (AFMC 2018), 2018 / pp.1-4|
|Publisher:||Australian Fluid Mechanics Society|
|Conference Name:||21st Australasian Fluid Mechanics Conference (10 Dec 2018 - 13 Dec 2018 : Adelaide, Australia)|
|E. R. Hassan and R. M. Kelso|
|Abstract:||This paper describes observations and measurements of the effect of cross-flow on the vorticity field of laminar vortex rings ejected from a circular pipe using particle-image velocimetry (PIV). We estimate positive-core circulation on the upstream side of the vortex ring and a negative circulation on the other side. Two pipe geometries are considered; one where the pipe exit is flush with a flat wall and one where the pipe exit is elevated above the wall. Vortex ring tilting is observed for both geometries. Observation of the circulation development of the vortex cores shows that the circulation growth rate of the positive (upstream) vortex core is always smaller in magnitude than that of the negative (downstream) core. This is due to interaction of the vortex ring with regions of flow containing negative vorticity at the pipe exit. In the flush-mounted case, this negative vorticity is contained in the laminar boundary layer that develops over the wall. In the elevated case a shear layer that forms over the top of the elevated pipe contributes negative vorticity to the flow. Observations of the evolving vorticity fields for both geometries show that the motion of the positive vortex core in the pipe-axial direction is impeded by the presence of the cross flow. This impediment is not observed for the negative core. This difference in the motion of the vortex-ring cores results in the tilting of the vortex ring.|
|Rights:||Commencing with 19AFMC, the Society holds copyright to papers which appear in the Proceedings. Prior to that, copyright resides with authors of the papers.|
|Appears in Collections:||Mechanical Engineering conference papers|
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