Investigation of the two-fluid turbulence characteristics by coupled simulation between quantum turbulence and normal-fluid turbulence

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03935
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Keio University
• Principal Investigator: Kobayashi Hiromichi 慶應義塾大学, 法学部(日吉), 教授 (60317336)
• Co-Investigator(Kenkyū-buntansha): 坪田 誠 大阪市立大学, 大学院理学研究科, 教授 (10197759)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 量子乱流 / 数値流体力学 / 超流動ヘリウム / 2流体結合 / 混相流

Outline of Final Research Achievements

Cryogenic liquid helium is in a two-fluid state in which inviscid superfluid and viscous normal-fluid are mixed. Experiments have shown three states: (1) both fluids are laminar; (2) superfluid is turbulent (quantum turbulence), but normal-fluids is laminar; (3) both fluids are turbulent. However, the details remain unclear. Thus, we investigate those characteristics by developing and implementing a two-fluid coupled simulation via mutual friction. Numerical analysis was performed assuming that superfluid is quantized vortices and normal-fluid is a viscous continuum (viscous fluid). It was found that we revealed phenomena such as flattening of normal fluid due to mutual friction by quantum turbulence, reduction of entrance length, anisotropic velocity fluctuation of laminar normal-fluid, and enhancement of turbulent intensity in two-fluid turbulence.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

極低温の液体ヘリウムは、MRI、核融合炉、リニアモーターカー、加速器におけるといった超電導磁石の冷却に利用されており、その特性解明はそのような冷却機器の性能向上に役立つ。また、2流体混合状態の物理現象の理解は、微粒子、噴霧、気泡といった分散相を含む２相流の理解にも資する。