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Abstracts
P3.2
Dynamics of quantized vortices before reconnection at finite
temperature
Andryushchenko Andrey, Kondaurova Luiza, Nemirovskii Sergey
Institute of Thermophysics SB RAS, Lavrentyev ave, 1, 630090, Novosibirsk,
Russia Novosibirsk and Novosibirsk University, Department of Physics
The goal of this paper is to investigate the dynamics of quantized vortex loops,
just before the reconnection at finite temperature. Modeling is performed on
the base of vortex filament method. It was discovered that the initial position
of vortices and the temperature strongly affect the dependence on time of
the minimum distance
δ
(
t
) between tips of two vortex loops. However, this
relationship takes a universal square-root form
δ
(
t
) = [(
k/
2
π
)
∗
(
t
∗ −
t
)]
1
/
2
at
distances smaller than the distances, satisfying the Schwarz reconnection criterion,
when the nonlocal contribution to the Biot–Savart equation becomes about equal
to the local contribution. In the “universal” stage, the nearest parts of vortices
form a pyramid-like structure with angles which neither depend on the initial
configuration nor on temperature.
P3.3
Theory of adiabatic fountain resonance with superfluid
4
He
Gary A. Williams
University of California, Los Angeles, CA 90095, USA
The theory of ”adiabatic fountain resonance” with superfluid
4
He is clarified. In
this geometry a film region between two silicon wafers glued at their outer edge
opens up to a central region with a free surface. We find that the resonance in
this system is not a Helmholtz resonance as claimed by Gasparini and co-workers,
but in fact is a 4th sound resonance. It occurs at relatively low frequency because
the thin silicon wafers flex appreciably from the pressure oscillations of the sound
wave. We raise questions about the ”giant proximity effect” claimed to have been
observed with this resonance.
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