Particle trajectories in thermal counterflow of superfluid helium in a wide channel of square cross section

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F16%3A10335139" target="_blank" >RIV/00216208:11320/16:10335139 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1063/1.4940980" target="_blank" >http://dx.doi.org/10.1063/1.4940980</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/1.4940980" target="_blank" >10.1063/1.4940980</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Particle trajectories in thermal counterflow of superfluid helium in a wide channel of square cross section

Popis výsledku v původním jazyce

The motion of micrometer-sized solid hydrogen particles in thermal counterflow of superfluid helium is studied experimentally by using the particle tracking velocimetry technique. The investigated quantum flow occurs in a square channel of 25 mm sides and 100 mm length, appreciably wider than those employed in previous related experiments. Flow velocities up to 10 mm/s are obtained, corresponding to temperatures between about 1.3 K and 2.1 K, and applied heat fluxes between ca. 50 W/m(2) and 500 W/m(2). The character of the obtained particle trajectories changes significantly as the imposed mean flow velocity increases. At thermal counterflow velocities lower than approximately 1 mm/s, the particle tracks appear straighter than at larger velocities. On the basis of the current understanding of the underlying physics, it is argued that the outcome is most likely due to the transition to the turbulent state of the investigated flow as, for narrower channels, this transition was reported to occur at larger velocities. The present results confirm that, at least in the parameter ranges investigated to date, the transition to turbulence in thermal counterflow depends on the geometry of the channel where this quantum flow develops. (C) 2016 AIP Publishing LLC.

Název v anglickém jazyce

Particle trajectories in thermal counterflow of superfluid helium in a wide channel of square cross section

Popis výsledku anglicky

The motion of micrometer-sized solid hydrogen particles in thermal counterflow of superfluid helium is studied experimentally by using the particle tracking velocimetry technique. The investigated quantum flow occurs in a square channel of 25 mm sides and 100 mm length, appreciably wider than those employed in previous related experiments. Flow velocities up to 10 mm/s are obtained, corresponding to temperatures between about 1.3 K and 2.1 K, and applied heat fluxes between ca. 50 W/m(2) and 500 W/m(2). The character of the obtained particle trajectories changes significantly as the imposed mean flow velocity increases. At thermal counterflow velocities lower than approximately 1 mm/s, the particle tracks appear straighter than at larger velocities. On the basis of the current understanding of the underlying physics, it is argued that the outcome is most likely due to the transition to the turbulent state of the investigated flow as, for narrower channels, this transition was reported to occur at larger velocities. The present results confirm that, at least in the parameter ranges investigated to date, the transition to turbulence in thermal counterflow depends on the geometry of the channel where this quantum flow develops. (C) 2016 AIP Publishing LLC.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BK - Mechanika tekutin

OECD FORD obor

—

Projekt

<a href="/cs/project/GAP203%2F11%2F0442" target="_blank" >GAP203/11/0442: Vizualizace proudění kapalného helia</a><br>

Návaznosti

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

Rok uplatnění

2016

Kód důvěrnosti údajů

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

Název periodika

Physics of Fluids

ISSN

1070-6631

e-ISSN

—

Svazek periodika

28

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

—

Kód UT WoS článku

000371286500033

EID výsledku v databázi Scopus

2-s2.0-84957989816