Coherent propagation of vortex rings at extremely high Reynolds numbers

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F22%3A10452857" target="_blank" >RIV/00216208:11320/22:10452857 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=2H4vervg5p" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=2H4vervg5p</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1017/jfm.2022.972" target="_blank" >10.1017/jfm.2022.972</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Coherent propagation of vortex rings at extremely high Reynolds numbers

Popis výsledku v původním jazyce

We take advantage of the extremely small kinematic viscosity of superfluid 4He to investigate the propagation of macroscopic vortex rings at Reynolds numbers between 2 x 10(4) and 4 x 10(6). These inhomogeneous flow structures are thermally generated by releasing short power pulses into a small volume of liquid, open to the surrounding bath through a vertical tube 2 mm in diameter. We study specifically the ring behaviour between 1.30 and 1.80 K using the flow visualization and second sound attenuation techniques. From the obtained data sets, containing more than 2600 realizations, we find that the rings remain well-defined in space and time for distances up to at least 40 tube diameters, and that their circulation depends significantly on the travelled distance, in a way similar to that observed for turbulent vortex rings propagating in Newtonian fluids. Additionally, the ring velocity and circulation appear to be influenced solely by a single, experimentally accessible parameter, combining the liquid temperature with the magnitude and duration of the power pulse. Overall, our results support the view that macroscopic vortex rings moving in superfluid He-4 closely resemble their Newtonian analogues, at least in the absence of significant thermal effects and at sufficiently large flow scales.

Název v anglickém jazyce

Coherent propagation of vortex rings at extremely high Reynolds numbers

Popis výsledku anglicky

We take advantage of the extremely small kinematic viscosity of superfluid 4He to investigate the propagation of macroscopic vortex rings at Reynolds numbers between 2 x 10(4) and 4 x 10(6). These inhomogeneous flow structures are thermally generated by releasing short power pulses into a small volume of liquid, open to the surrounding bath through a vertical tube 2 mm in diameter. We study specifically the ring behaviour between 1.30 and 1.80 K using the flow visualization and second sound attenuation techniques. From the obtained data sets, containing more than 2600 realizations, we find that the rings remain well-defined in space and time for distances up to at least 40 tube diameters, and that their circulation depends significantly on the travelled distance, in a way similar to that observed for turbulent vortex rings propagating in Newtonian fluids. Additionally, the ring velocity and circulation appear to be influenced solely by a single, experimentally accessible parameter, combining the liquid temperature with the magnitude and duration of the power pulse. Overall, our results support the view that macroscopic vortex rings moving in superfluid He-4 closely resemble their Newtonian analogues, at least in the absence of significant thermal effects and at sufficiently large flow scales.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

<a href="/cs/project/GA19-00939S" target="_blank" >GA19-00939S: Dynamika velkých vírů v kvantové turbulenci</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Fluid Mechanics

ISSN

0022-1120

e-ISSN

1469-7645

Svazek periodika

953

Číslo periodika v rámci svazku

9 December 2022

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

26

Strana od-do

A28

Kód UT WoS článku

000895808700001

EID výsledku v databázi Scopus

2-s2.0-85143893254