A numerical study of vortex ring formation at the edge of a circular tube

1994 ◽  
Vol 276 ◽  
pp. 139-161 ◽  
Author(s):  
Monika Nitsche ◽  
Robert Krasny
Keyword(s):  
Vortex Ring ◽  
Circular Tube ◽  
Numerical Study ◽  
Similarity Theory ◽  
Vortex Sheet ◽  
Ring Formation ◽  
Vortex Ring Formation ◽  
Axisymmetric Vortex ◽  
Basic Features ◽  
Starting Flow

An axisymmetric vortex-sheet model is applied to simulate an experiment of Didden (1979) in which a moving piston forces fluid from a circular tube, leading to the formation of a vortex ring. Comparison between simulation and experiment indicates that the model captures the basic features of the ring formation process. The computed results support the experimental finding that the ring trajectory and the circulation shedding rate do not behave as predicted by similarity theory for starting flow past a sharp edge. The factors responsible for the discrepancy between theory and observation are discussed.

scholarly journals Investigation of vortex ring formation with account of generator piston motion

2017 ◽  
Vol 208 ◽  
pp. 012045 ◽  
Author(s):  
I V Khramtsov ◽  
VV Palchikovskiy ◽  
A A Siner ◽  
Yu V Bersenev
Keyword(s):  
Vortex Ring ◽  
Ring Formation ◽  
Piston Motion ◽  
Vortex Ring Formation

scholarly journals Volumetric flow imaging reveals the importance of vortex ring formation in squid swimming tail-first and arms-first

2015 ◽  
Vol 219 (3) ◽  
pp. 392-403 ◽  
Author(s):  
Ian K. Bartol ◽  
Paul S. Krueger ◽  
Rachel A. Jastrebsky ◽  
Sheila Williams ◽  
Joseph T. Thompson
Keyword(s):  
Vortex Ring ◽  
Ring Formation ◽  
Flow Imaging ◽  
Vortex Ring Formation

Free Vortex Ring Formation in the Left Atrium Originating in the Left Auricle

1992 ◽  
Vol 5 (3) ◽  
pp. 274-276 ◽  
Author(s):  
R.A. Mikael Kortz ◽  
Ben J. Delemarre ◽  
Hans Bot ◽  
Cees A. Visser
Keyword(s):  
Left Atrium ◽  
Vortex Ring ◽  
Ring Formation ◽  
Left Auricle ◽  
Free Vortex ◽  
Vortex Ring Formation

Circulation Generation and Vortex Ring Formation by Conic Nozzles

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Moshe Rosenfeld ◽  
Kakani Katija ◽  
John O. Dabiri
Keyword(s):  
Vortex Ring ◽  
Vortex Generator ◽  
Ring Formation ◽  
Vortex Rings ◽  
Two Dimensional ◽  
One Dimensional ◽  
Dimensional Flow ◽  
Vortex Ring Formation ◽  
Exit Nozzle ◽  
Two Dimensional Flow

Vortex rings are one of the fundamental flow structures in nature. In this paper, the generation of circulation and vortex rings by a vortex generator with a static converging conic nozzle exit is studied numerically. Conic nozzles can manipulate circulation and other flow invariants by accelerating the flow, increasing the Reynolds number, and by establishing a two-dimensional flow at the exit. The increase in the circulation efflux is accompanied by an increase in the vortex circulation. A novel normalization method is suggested to differentiate between two contributions to the circulation generation: a one-dimensional slug-type flow contribution and an inherently two-dimensional flow contribution. The one-dimensional contribution to the circulation increases with the square of the centerline exit velocity, while the two-dimensional contribution increases linearly with the decrease in the exit diameter. The two-dimensional flow contribution to the circulation production is not limited to the impulsive initiation of the flow only (as in straight tube vortex generators), but it persists during the entire ejection. The two-dimensional contribution can reach as much as 44% of the total circulation (in the case of an orifice). The present study offers evidences on the importance of the vortex generator geometry, and in particular, the exit configuration on the emerging flow, circulation generation, and vortex ring formation. It is shown that both total and vortex ring circulations can be controlled to some extent by the shape of the exit nozzle.

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