An experimental study of turbulent vortex rings in superfluid He-4

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F20%3A10413811" target="_blank" >RIV/00216208:11320/20:10413811 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=Yrl2oGGdoL" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=Yrl2oGGdoL</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1017/jfm.2020.96" target="_blank" >10.1017/jfm.2020.96</a>

Jazyk výsledku

angličtina

Název v původním jazyce

An experimental study of turbulent vortex rings in superfluid He-4

Popis výsledku v původním jazyce

Macroscopic vortex rings are generated thermally in superfluid He-4, between 1.28 and 1.95 K, by applying a brief voltage pulse to a resistive heater located below a circular vertical tube 5 mm in diameter and 20 mm high. The rings form above the tube and propagate upward with velocities of the order of , resulting in Reynolds numbers up to . We visualize their cross-section, of size comparable with the tube diameter, by capturing the motions of relatively small solid deuterium particles, previously dispersed in the quiescent bath of superfluid He-4. We employ particle positions and velocities to compute the Lagrangian pseudovorticity, which can be seen as a measure of the ring strength and which allows us to identify and track these objects. We thus obtain time-dependent sizes, positions and velocities of the vortex rings. We show that, in the range of investigated parameters, these rings behave as if they were turbulent vortex rings moving in classical viscous fluids, at least in the direction of ring propagation. The outcome reinforces the view that the study of turbulent flows of superfluid He-4 is not only interesting in its own right, but that it can also contribute to our current understanding of fluid turbulence in general.

Název v anglickém jazyce

An experimental study of turbulent vortex rings in superfluid He-4

Popis výsledku anglicky

Macroscopic vortex rings are generated thermally in superfluid He-4, between 1.28 and 1.95 K, by applying a brief voltage pulse to a resistive heater located below a circular vertical tube 5 mm in diameter and 20 mm high. The rings form above the tube and propagate upward with velocities of the order of , resulting in Reynolds numbers up to . We visualize their cross-section, of size comparable with the tube diameter, by capturing the motions of relatively small solid deuterium particles, previously dispersed in the quiescent bath of superfluid He-4. We employ particle positions and velocities to compute the Lagrangian pseudovorticity, which can be seen as a measure of the ring strength and which allows us to identify and track these objects. We thus obtain time-dependent sizes, positions and velocities of the vortex rings. We show that, in the range of investigated parameters, these rings behave as if they were turbulent vortex rings moving in classical viscous fluids, at least in the direction of ring propagation. The outcome reinforces the view that the study of turbulent flows of superfluid He-4 is not only interesting in its own right, but that it can also contribute to our current understanding of fluid turbulence in general.

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

2020

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

—

Svazek periodika

889

Číslo periodika v rámci svazku

28.01.2020

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

25

Strana od-do

A24

Kód UT WoS článku

000515189500001

EID výsledku v databázi Scopus

2-s2.0-85081112646