Particle dynamics in wall-bounded thermal counterflow of superfluid helium

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F17%3A10368512" target="_blank" >RIV/00216208:11320/17:10368512 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1063/1.4984913" target="_blank" >http://dx.doi.org/10.1063/1.4984913</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/1.4984913" target="_blank" >10.1063/1.4984913</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Particle dynamics in wall-bounded thermal counterflow of superfluid helium

Popis výsledku v původním jazyce

The motions of relatively small particles in wall-bounded thermal counterflow of superfluid helium are experimentally investigated, above 1 K, by using the particle tracking velocimetry technique. The effect of a solid boundary on this quantum flow has received little attention to date, and the focus here is on the corresponding flow-induced particle dynamics. The velocity and velocity difference statistical distributions of the particles are computed at length scales straddling two orders of magnitude across the mean distance between quantized vortices, the quantum length scale of the flow. The imposed counterflow velocity ranges between about 2 and 7 mm/s, resulting in suitably defined Reynolds numbers up to 20 000. The distributions are found to be wider in the bulk than close to the solid boundary, at small enough scales, and this suggests that the mean distance between the vortices increases with the distance from the wall. The outcome reinforces the view, supported to date solely by numerical simulations, that in thermal counterflow quantized vortices are not homogenously distributed in the channel and that they preferentially concentrate close to its walls. Boundary layers might therefore also exist in quantum flows, although some of their features appear to be significantly different from those attributed towall-bounded flows of viscous fluids, due to the presence of quantized vortices.

Název v anglickém jazyce

Particle dynamics in wall-bounded thermal counterflow of superfluid helium

Popis výsledku anglicky

The motions of relatively small particles in wall-bounded thermal counterflow of superfluid helium are experimentally investigated, above 1 K, by using the particle tracking velocimetry technique. The effect of a solid boundary on this quantum flow has received little attention to date, and the focus here is on the corresponding flow-induced particle dynamics. The velocity and velocity difference statistical distributions of the particles are computed at length scales straddling two orders of magnitude across the mean distance between quantized vortices, the quantum length scale of the flow. The imposed counterflow velocity ranges between about 2 and 7 mm/s, resulting in suitably defined Reynolds numbers up to 20 000. The distributions are found to be wider in the bulk than close to the solid boundary, at small enough scales, and this suggests that the mean distance between the vortices increases with the distance from the wall. The outcome reinforces the view, supported to date solely by numerical simulations, that in thermal counterflow quantized vortices are not homogenously distributed in the channel and that they preferentially concentrate close to its walls. Boundary layers might therefore also exist in quantum flows, although some of their features appear to be significantly different from those attributed towall-bounded flows of viscous fluids, due to the presence of quantized vortices.

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/GA16-00580S" target="_blank" >GA16-00580S: Hranice kvantové turbulence</a><br>

Návaznosti

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

Rok uplatnění

2017

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

29

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

9

Strana od-do

—

Kód UT WoS článku

000404636900031

EID výsledku v databázi Scopus

2-s2.0-85020306657