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Title: Characterizing vortex tangle properties in steady-state He II counterflow using particle tracking velocimetry

Abstract

Historically, there has been little faith in particle tracking velocimetry (PTV) as a tool to make quantitative measurements of thermal counterflow in He II, since tracer particle motion is complicated by influences from the normal fluid, superfluid, and quantized vortex lines, or a combination thereof. Recently, we introduced a scheme for differentiating particles trapped on vortices (G1) from particles entrained by the normal fluid (G2). In this paper, we apply this scheme to demonstrate the utility of PTV for quantitative measurements of vortex dynamics in He II counterflow.We estimate Ι, the mean vortex line spacing, using G2 velocity data, and c 2, a parameter related to the mean curvature radius of vortices and energy dissipation in quantum turbulence, using G1 velocity data. We find that both estimations show good agreement with existing measurements that were obtained using traditional experimental methods. This is of particular consequence since these parameters likely vary in space, and PTV offers the advantage of spatial resolution. Furthermore, we also show a direct link between power-law tails in transverse particle velocity probability density functions (PDFs) and reconnection of vortex lines on which G1 particles are trapped.

Authors:
 [1];  [1]
  1. Florida State Univ., Tallahassee, FL (United States)
Publication Date:
Research Org.:
Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab.
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1493665
Alternate Identifier(s):
OSTI ID: 1493852
Grant/Contract Number:  
FG02-96ER40952
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Fluids
Additional Journal Information:
Journal Volume: 4; Journal Issue: 2; Journal ID: ISSN 2469-990X
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Turbulence; Vortices; Superfluid Helium-4; Flow Visualization

Citation Formats

Mastracci, Brian, and Guo, Wei. Characterizing vortex tangle properties in steady-state He II counterflow using particle tracking velocimetry. United States: N. p., 2019. Web. doi:10.1103/PhysRevFluids.4.023301.
Mastracci, Brian, & Guo, Wei. Characterizing vortex tangle properties in steady-state He II counterflow using particle tracking velocimetry. United States. doi:10.1103/PhysRevFluids.4.023301.
Mastracci, Brian, and Guo, Wei. Thu . "Characterizing vortex tangle properties in steady-state He II counterflow using particle tracking velocimetry". United States. doi:10.1103/PhysRevFluids.4.023301.
@article{osti_1493665,
title = {Characterizing vortex tangle properties in steady-state He II counterflow using particle tracking velocimetry},
author = {Mastracci, Brian and Guo, Wei},
abstractNote = {Historically, there has been little faith in particle tracking velocimetry (PTV) as a tool to make quantitative measurements of thermal counterflow in He II, since tracer particle motion is complicated by influences from the normal fluid, superfluid, and quantized vortex lines, or a combination thereof. Recently, we introduced a scheme for differentiating particles trapped on vortices (G1) from particles entrained by the normal fluid (G2). In this paper, we apply this scheme to demonstrate the utility of PTV for quantitative measurements of vortex dynamics in He II counterflow.We estimate Ι, the mean vortex line spacing, using G2 velocity data, and c2, a parameter related to the mean curvature radius of vortices and energy dissipation in quantum turbulence, using G1 velocity data. We find that both estimations show good agreement with existing measurements that were obtained using traditional experimental methods. This is of particular consequence since these parameters likely vary in space, and PTV offers the advantage of spatial resolution. Furthermore, we also show a direct link between power-law tails in transverse particle velocity probability density functions (PDFs) and reconnection of vortex lines on which G1 particles are trapped.},
doi = {10.1103/PhysRevFluids.4.023301},
journal = {Physical Review Fluids},
number = 2,
volume = 4,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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This content will become publicly available on February 7, 2020
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