Formation of polygonal vortex ring caused by interfacial instability

2023 Fiscal Year Final Research Report

• Project/Area Number: 18K03572
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
• Research Institution: Nara Women's University (2023); Fukuoka Institute of Technology (2018-2022)
• Principal Investigator: Shimokawa Michiko 奈良女子大学, 自然科学系, 准教授 (80554419)
• Co-Investigator(Kenkyū-buntansha): 坂口 英継 九州大学, 総合理工学研究院, 准教授 (90192591)
• Project Period (FY): 2018-04-01 – 2024-03-31
• Keywords: 渦輪 / 界面不安定 / 重力不安定

Outline of Final Research Achievements

A falling droplet breaks up into several droplets, after the droplet spontaneously deforms into a vortex ring as it falls in a viscous fluid. Although this phenomenon has been known for more than 100 years, its dynamics have not been well understood because it is an unsteady system in which the droplet shape and settling velocity change with time. We, therefore, proposed to understand its dynamics by studying of the vortex ring instability that causes the droplet to break up.
During the period of this project, we have identified the physical quantities to determine a number of a breakup of a droplet. In addition, we have proposed a new phenomenological model to include the effect of the vortex ring instability, and we have considered the dynamics by comparing our experimental results with those obtained from the model.

Free Research Field

非平衡物理学

Academic Significance and Societal Importance of the Research Achievements

本研究は外力により駆動する液滴の分裂現象に着目した基礎研究である。液滴の分裂現象はプリンターの印刷技術の向上や自動車のエンジンの発火効率の上昇など工学技術の発展を考えるうえで重要な基礎研究であるといえる。そのため，本研究で得られた知見を発展させることで工学的応用が期待される。