Study of Suction vortex formation using superfluid Helium-4

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03865
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
• Research Institution: Osaka Metropolitan University (2022); Osaka City University (2020-2021)
• Principal Investigator: Obaraq Ken 大阪公立大学, 大学院理学研究科, 講師 (50347481)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超流動 / 吸込渦 / 量子渦 / 循環 / 量子乱流

Outline of Final Research Achievements

I have studied Suction vortices generated in superfluid He. The quantum vortex density was measured by second resonance in the path across the vortex core, and at the same time, the horizontal circulation was directly measured by ultrasonic velocimetry in the path not passing through the core.
The two measurements revealed that the quantum vortex-lines in the suction vortex are nearly horizontal and wraps around the vortex core. This study is the first case that clarified the structure of vorticity of the suction vortex not only in superfluids but also in ordinary liquids.

Free Research Field

超流動・低温工学

Academic Significance and Societal Importance of the Research Achievements

流体力学は数々の流体現象を明らかにしてきたが，吸込渦という鉛直流と水平回転流が共存している流れについては多くのことは知られていなかった．その理由は，中心付近の流れが極端に強くなるため，風洞実験・可視化実験のようなテクニックが使えなかったからである．この研究では超流動特有の音波（第２音波および超音波）と，超流動特有の循環の量子化条件を用いることで，もっとも身近な渦の一つの内部の流れの構造を明らかにした．