Dynamics of monodispersed bubble generation skirting hydrodynamically crowded circumstance

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01248
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: The University of Tokyo (2023); Kyoto Institute of Technology (2021-2022)
• Principal Investigator: Watamura Tomoaki 東京大学, 大学院工学系研究科(工学部), 講師 (40777736)
• Co-Investigator(Kenkyū-buntansha): 小笠原 紀行 大阪公立大学, 大学院工学研究科, 准教授 (00552184) ; 大友 涼子 関西大学, システム理工学部, 准教授 (00726862) ; 杉山 和靖 大阪大学, 大学院基礎工学研究科, 教授 (50466786)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 混相流 / 気泡 / 濃度

Outline of Final Research Achievements

In a particle or bubble suspended fluids, a very large number of small dispersed bodies form a texture motion of a swarm. Such a texture motion is caused by a gravity-driven hydrodynamic instability and depends on the interbubble distance. However, it is unknown why the bubble cascade is observed only in stout beer with nitrogen, such as Guinness beer. To address this question via a priori estimation, here, we develop a mathematical continuum model of film flow in bubbly liquid, uncovering the essential dynamics among many physical processes occurring simultaneously in a glass. We perform a numerical simulation of the distribution of massless Lagrangian particles in an inclined container. We investigate the effects of particle concentration, inclination angle, particle diameter, and container size on the cascading film flow. The results reveal that the motion and waviness of clear-fluid film can be successfully estimated a priori to experiments or simulations.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

分散体と連続相との間に生じる密度差対流は，化学反応装置や曝気槽内部に生じるため工学的に重要な現象であるが，密度差対流の不安定発生条件や分散体相変化の影響が不明であり，流動の制御が不可能であった．本研究では数値計算により流動不安定の発生条件を予測した．また，清澄分離のモデル化からも流動のスケーリング則を提案し，不安定の発生臨界を代数的に推定できることを世界で初めて示した．この結果は，Review of Modern Physicsにて紹介されたため，当該研究分野にインパクトを与えるものと言える．今後，本研究成果と，閉空間内における分散体の成長を考慮することで，現象理解が進むことが期待できる．