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Abstracts
P3.10
Study of particle motion in He II counterflow across a wide heat flux
range
Mastracci Brian(1,2), Takada Suguru(3), Guo Wei(1,2)
1) National High Magnetic Field Laboratory, Florida State University,
Tallahassee, FL 32310, USA
2) Department of Mechanical Engineering, FAMU-FSU College of Engineering,
Tallahassee, FL 32310, USA
3) National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
Some discrepancy exists in the results of He II counterflow experiments obtained
using PIV when compared with those obtained using PTV. It is suggested that
this is due to differing applied heat flux ranges. An earlier PTV experiment in our
lab attempted to test this model but the applied heat flux did not actually overlap
with any PIV experiments. We report a PTV study of solid D2 particle motion
in counterflow, and the heat flux range overlaps that of all previous visualization
studies. The observed particle velocity distribution transitions from a two-peak
structure to a single peak centered at 0.5vn as the heat flux is increased. The
temperature dependence of this transition is examined.
P3.11
Statistical measurement of counterflow turbulence in superfluid
helium-4 using He
2
∗
tracer-line tracking technique
J. Gao(1,2), E. Varga(3,2), W. Guo(1,2), and W. F. Vinen(4)
(1) Mechanical Engineering Department, Florida State University, Tallahassee,
Florida State, 32310, USA
(2) National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive,
Tallahassee, Florida State, 32310, USA
(3) Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3,
Prague, Czech Republic
(4) School of Physics and Astronomy, University of Birmingham, Birmingham
B15 2TT, United Kingdom
A high precision flow visualization technique based on the tracking of thin lines
of
He
2
∗
molecular tracers has been developed in our lab. We have applied
this technique in the study of steady-state counterflow turbulence in superfluid
helium-4. Besides mapping out the velocity profile in the flow channel, we can
also determine turbulence statistics such as the velocity distribution functions
and the structure functions based on the analysis of tracer-line mages. We report
how these statistics vary with temperature and heat flux. We also discuss our
on-going development of an advanced tracer-line image processing method.
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