Numerical modelling and experimental study of transitions in spherical Couette flow

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04294
• 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: Kansai University
• Principal Investigator: Itano Tomoaki 関西大学, システム理工学部, 教授 (30335187)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 球面クエット流 / 数値計算 / 可視化

Outline of Final Research Achievements

Designing and assembling the experimental apparatus under reference to previous studies, the experimental setup was extended to allow the rotation of the entire system and the observation of the flow through a window at the bottom of the apparatus. By injecting flakes to visualise the flow, the axisymmetric flow and the spiral state can be confirmed in the transition. A high-precision torque meter was employed to measure the transition Reynolds number, which was compared with previous research. A simulation code for viscous fluid flow between double concentric spheres based on the Navier-Stokes equations was also developed on the basis of the spectral method. The complementary validity of numerical and experimental results was quantitatively verified.

Free Research Field

流体物理学

Academic Significance and Societal Importance of the Research Achievements

極と赤道付近で発生源が異なる不安定性が競合し、半径比に依存して不安定化因子の優越が変化し複雑な遷移を示すクエット流に対して、遷移レイノルズ数を理論的にも実験的にも検証することができた。先行研究において古典的な流れの可視化により遷移が同定できていいた謎が、流れの中を並進・回転するフレークを運動を数値的に解析することで明らかになった。また熱的因子が加わった場合、スパイラル状態が球殻内熱対流に連続的に接続することが数値計算から明らかになった。