MULTI-POINT LAGRANGIAN VELOCITY ESTIMATES

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F18%3A10389793" target="_blank" >RIV/00216208:11320/18:10389793 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.14311/TPFM.2018.038" target="_blank" >https://doi.org/10.14311/TPFM.2018.038</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.14311/TPFM.2018.038" target="_blank" >10.14311/TPFM.2018.038</a>

Jazyk výsledku

angličtina

Název v původním jazyce

MULTI-POINT LAGRANGIAN VELOCITY ESTIMATES

Popis výsledku v původním jazyce

Micron-sized particles of solid deuterium are suspended in superfluid He-4 (He II) and their time-dependent positions are captured by using the particle tracking velocimetry technique. As the computation of the particle velocities from the obtained positions can be noisy, mainly due to experimental uncertainties, we compare here four different numerical approaches to estimate the velocities. We choose, as a test case, the flow of He II occurring between two grids oscillating in phase, which, in the range of investigated parameters, display classical like features, very similar to those found in turbulent flows of viscous fluids. We focus on algorithms that consider multiple particle positions for the estimation of a single velocity. Although the velocities computed by the chosen procedures are relatively similar, we find that the statistical distributions of the corresponding velocity increments, i.e., coarse-grained accelerations, depend on the choice of the algorithm and its parameters in a more pronounced way than in the case of velocities. It follows therefore that the numerical approach employed to estimate Lagrangian velocity increments should be chosen carefully on the basis of the physical problem being investigated.

Název v anglickém jazyce

MULTI-POINT LAGRANGIAN VELOCITY ESTIMATES

Popis výsledku anglicky

Micron-sized particles of solid deuterium are suspended in superfluid He-4 (He II) and their time-dependent positions are captured by using the particle tracking velocimetry technique. As the computation of the particle velocities from the obtained positions can be noisy, mainly due to experimental uncertainties, we compare here four different numerical approaches to estimate the velocities. We choose, as a test case, the flow of He II occurring between two grids oscillating in phase, which, in the range of investigated parameters, display classical like features, very similar to those found in turbulent flows of viscous fluids. We focus on algorithms that consider multiple particle positions for the estimation of a single velocity. Although the velocities computed by the chosen procedures are relatively similar, we find that the statistical distributions of the corresponding velocity increments, i.e., coarse-grained accelerations, depend on the choice of the algorithm and its parameters in a more pronounced way than in the case of velocities. It follows therefore that the numerical approach employed to estimate Lagrangian velocity increments should be chosen carefully on the basis of the physical problem being investigated.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

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

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2018

Kód důvěrnosti údajů

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

Název statě ve sborníku

TOPICAL PROBLEMS OF FLUID MECHANICS 2018

ISBN

978-80-87012-65-9

ISSN

2336-5781

e-ISSN

neuvedeno

Počet stran výsledku

10

Strana od-do

281-290

Název nakladatele

ACAD SCI CZECH REPUBLIC, INST THERMOMECHANICS

Místo vydání

PRAGUE 8

Místo konání akce

Prague

Datum konání akce

21. 2. 2018

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000457661300038