scholarly journals Axisymmetric contour dynamics for buoyant vortex rings

2020 ◽  
Vol 887 ◽  
Author(s):  
Ching Chang ◽  
Stefan G. Llewellyn Smith
Keyword(s):  
Vortex Rings ◽  
Contour Dynamics ◽  
Image Position ◽  
Buoyant Vortex Rings

Laminar to Turbulent Buoyant Vortex Ring Regime in Terms of Reynolds Number, Bond Number, and Weber Number

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Xueying Yan ◽  
Rupp Carriveau ◽  
David S. K. Ting
Keyword(s):  
Reynolds Number ◽  
Vortex Ring ◽  
Weber Number ◽  
High Speed ◽  
Reynolds Numbers ◽  
Bond Number ◽  
Vortex Rings ◽  
Transition Regime ◽  
Turbulent Vortex ◽  
Buoyant Vortex Rings

When buoyant vortex rings form, azimuthal disturbances occur on their surface. When the magnitude of the disturbance is sufficiently high, the ring will become turbulent. This paper establishes conditions for categorization of a buoyant vortex ring as laminar, transitional, or turbulent. The transition regime of enclosed-air buoyant vortex rings rising in still water was examined experimentally via two high-speed cameras. Sequences of the recorded pictures were analyzed using matlab. Key observations were summarized as follows: for Reynolds number lower than 14,000, Bond number below 30, and Weber number below 50, the vortex ring could not be produced. A transition regime was observed for Reynolds numbers between 40,000 and 70,000, Bond numbers between 120 and 280, and Weber number between 400 and 800. Below this range, only laminar vortex rings were observed, and above, only turbulent vortex rings.

Experimental study of buoyant vortex rings

1983 ◽  
Vol 24 (1) ◽  
pp. 16-21 ◽  
Author(s):  
B. I. Zaslavskii ◽  
I. M. Sotnikov
Keyword(s):  
Experimental Study ◽  
Vortex Rings ◽  
Buoyant Vortex Rings

scholarly journals Collision of vortex rings upon V-walls

2020 ◽  
Vol 899 ◽  
Author(s):  
T. H. New ◽  
J. Long ◽  
B. Zang ◽  
Shengxian Shi
Keyword(s):  
Vortex Rings ◽  
Image Position

Abstract

Drag of buoyant vortex rings

2015 ◽  
Vol 92 (4) ◽  
Author(s):  
Ahmadreza Vasel-Be-Hagh ◽  
Rupp Carriveau ◽  
David S.-K. Ting ◽  
John Stewart Turner
Keyword(s):  
Vortex Rings ◽  
Buoyant Vortex Rings

Inviscid and viscous global stability of vortex rings

2020 ◽  
Vol 902 ◽  
Author(s):  
Naveen Balakrishna ◽  
Joseph Mathew ◽  
Arnab Samanta
Keyword(s):  
Global Stability ◽  
Vortex Rings ◽  
Image Position

Abstract

scholarly journals Nested contour dynamics models for axisymmetric vortex rings and vortex wakes

2014 ◽  
Vol 748 ◽  
pp. 521-548 ◽  
Author(s):  
Clara O’Farrell ◽  
John O. Dabiri
Keyword(s):  
Vortex Formation ◽  
Computational Cost ◽  
Small Region ◽  
Two Dimensions ◽  
Vortex Rings ◽  
Contour Dynamics ◽  
Piston Cylinder ◽  
Axisymmetric Vortex ◽  
Contour Models ◽  
Perturbation Size

AbstractInviscid models for vortex rings and dipoles are constructed using nested patches of vorticity. These models constitute more realistic approximations to experimental vortex rings and dipoles than the single-contour models of Norbury and Pierrehumbert, and nested contour dynamics algorithms allow their simulation with low computational cost. In two dimensions, nested-contour models for the analytical Lamb dipole are constructed. In the axisymmetric case, a family of models for vortex rings generated by a piston–cylinder apparatus at different stroke ratios is constructed from experimental data. The perturbation response of this family is considered by the introduction of a small region of vorticity at the rear of the vortex, which mimics the addition of circulation to a growing vortex ring by a feeding shear layer. Model vortex rings are found to either accept the additional circulation or shed vorticity into a tail, depending on the perturbation size. A change in the behaviour of the model vortex rings is identified at a stroke ratio of three, when it is found that the maximum relative perturbation size vortex rings can accept becomes approximately constant. We hypothesise that this change in response is related to pinch-off, and that pinch-off might be understood and predicted based on the perturbation responses of model vortex rings. In particular, we suggest that a perturbation response-based framework can be useful in understanding vortex formation in biological flows.

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