Statistical property in Quantum turbulence and its universality

2023 Fiscal Year Final Research Report

• Project/Area Number: 19H00747
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Nagoya University
• Principal Investigator: TSUJI Yoshiyuki 名古屋大学, 工学研究科, 教授 (00252255)
• Co-Investigator(Kenkyū-buntansha): 山本 義暢 山梨大学, 大学院総合研究部, 准教授 (40377809)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 量子乱流 / 高レイノルズ数乱流 / 乱流の普遍性

Outline of Final Research Achievements

The measurement system of three velocity components of fluid flow in space is realized with four high-speed cameras and CW laser. Small-scale turbulent structures and vortex sheet are captured by the Q-criteria based on velocity gradient tensor. Small particle trajectories in super fluid were analyzed and they are characterized by the local curvatures. It was found that the PDF of curvature is similar with that of classical turbulence. However, it differs between two and three dimensional space. The local curvature can also characterize the interaction of particles with quantum vortex. The separation distance between quantum vortexes can be estimated by the variance of particle position along the trajectories and Hurst exponent. As a new visualization system, it was confirmed that the helium excimer can be used as tracer particles in super fluid which is generated by the discharge in liquid.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

量子乱流における流動の特性を古典乱流場で用いられた統計的手法により解析することで、広く乱流の特性を理解できる道筋を示せた。流体乱流の普遍的理解に貢献できるものと考えている。ヘリウムの流動特性を理解することは、ヘリウムを用いた冷却技術の改善にも寄与することが期待される。核融合炉における超電導マグネット、量子コンピュータの基盤冷却など繊細な部位の効率的な熱除去には、量子乱流の特性を理解することが不可欠である。本研究での成果は、それらの技術開発に貢献できる。