QFS 2016 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 4 He 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)

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