An experimental study of turbulent vortex rings in superfluid 4He

2020 ◽  
Vol 889 ◽  
Author(s):  
P. Švančara ◽  
M. Pavelka ◽  
M. La Mantia
Keyword(s):  
Experimental Study ◽  
Superfluid 4He ◽  
Vortex Rings ◽  
Turbulent Vortex ◽  
Image Position

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

Experimental Study of the Nonlinear Second Sound Wave Interaction in Superfluid 4He

2006 ◽  
Vol 145 (1-4) ◽  
pp. 155-164 ◽  
Author(s):  
V. B. Efimov ◽  
A. N. Ganshin ◽  
P. V. E. McClintock ◽  
G. V. Kolmakov ◽  
L. P. Mezhov-Deglin
Keyword(s):  
Experimental Study ◽  
Sound Wave ◽  
Wave Interaction ◽  
Superfluid 4He ◽  
Second Sound

Turbulent vortex rings

1974 ◽  
Vol 64 (2) ◽  
pp. 227-240 ◽  
Author(s):  
T. Maxworthy
Keyword(s):  
Growth Process ◽  
Slow Growth ◽  
Separated Flow ◽  
Vortex Rings ◽  
Experimental Accuracy ◽  
Turbulent Vortex ◽  
Viscous Forces ◽  
A Value ◽  
Entrainment Coefficient ◽  
Scale Turbulence

We consider the motion of the mass of fluid ejected through a sharp-edged orifice by the motion of a piston. The vorticity formed by viscous forces within the separated flow at the sharp edge rolls up to form a concentrated vortex which, after a development period, consists of a core of very fine scale turbulence surrounded by a co-moving bubble of much larger scale turbulence. This bubble entrains outer fluid, mixes with it, and deposits the majority into a wake together with some small fraction of the total vorticity of the ring. Enough fluid is retained to account for the slow growth of the whole fluid mass. A theory which takes account of both the growth process and the loss of vorticity is proposed. By comparison with experimental measurements we have determined that the entrainment coefficient for turbulent vortex rings has a value equal to 0.011 ± 0.001, while their effective drag coefficient is 0.09 ± 0.01. These results seem to be independent of Reynolds number to within experimental accuracy.

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

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