QFS2016 Book of Abstracts

Abstracts

P3.16

Transition to turbulence and streamwise inhomogeneity of

counterflowing He4.

Varga E.(1), Babuin S.(2), L’Vov V.S.(3), Pomyalov A.(3), Skrbek L(1)

1) Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu

3, 121 16, Prague, Czech Republic

2) Institute of Physics ASCR, Na Slovance 2, 182 21 Prague, Czech Republic

3) The Weizmann Institute of Science, Department of Chemical Physics, Rehovot

76100 Israel

We report preliminary results of the complementary experimental and numerical

studies of the streamwise vortex lines density (VLD) distribution in counterflowing

He4. The experiment is set up in a long square channel with VLD and local

temperature measured in three streamwise locations. In the steady state we

observe nearly streamwise-homogeneous VLD. Experimental second sound data

as well as numerical data (vortex filament method in a long planar channel

starting with seeding vortices localized in multiple locations) show that the initial

build up pattern of VLD displays complex features depending on the position in

the channel, but the tangle properties appear uniform along the channel.

P3.17

Logarithmic velocity profile of wall-bounded quantum turbulence in

superfluid

Satoshi Yui(1), Kazuya Fujimoto(2), and Makoto Tsubota(1)

1) Osaka City University, Faculty of Science, Department of Physics, 3-3-138

Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan

2) The University of Tokyo, Faculty of Science, Department of Physics, Hongo

7-3-1, Bunkyo-ku, Tokyo 113-8654, Japan

In the filed of hydrodynamics, the logarithmic velocity profile has been studied

as one of the most important statistical law near a solid surface. However, it

has been unknown whether or not quantum turbulence exhibits the similar law.

This study shows that the logarithmic velocity profile appears in wall-bounded

quantum turbulence [1]. We performed the numerical simulation of quantum

turbulence between the two parallel plates by using the vortex filament

model. We investigated the configuration and dynamics of the inhomogeneous

vortex tangle to find the characteristic behavior of the logarithmic velocity profile.

[1] S. Yui, K. Fujimoto, and M. Tsubota, Phys. Rev. B 92, 224513 (2015)