JFM系列研讨会 | 液滴冻结
文摘
教育
2024-02-29 10:00
中国澳门
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日期: 2024年3月1日，星期五，4:00 PM（伦敦时间）
2024年3月2日，星期六，12:00 AM（北京时间）
An immersed soft particle or oil droplet is severely deformed when engulfed into an advancing ice front. This deformation strongly depends on the engulfment velocity, even forming pointy-tip shapes for low velocities. We found that such singular deformations are mediated by interfacial flows in nanometric thin liquid films separating the nonsolidifying dispersed soft particles or droplets and the solidifying bulk. The competing forces in the thin film originate from the disjoining pressure and the surface tension gradient (Marangoni forces). We analytically modelled the fluid flow in these intervening thin films, using a lubrication approximation in the boundary layers. In an exact analytical calculation and with a formal analogy to a nonlinear pendulum, we then related the fluid flow to the deformation sustained by the dispersed droplet. We find it astounding that the nanoscopic interaction (van der Waals forces, disjoining pressure) determines the shape of the macroscopic immersed soft particle or droplet.We then extended this line of research to the interaction of several immersed soft particles or droplets over which a solidification front is passing. This time it is the relative thermal conductivity of the soft particles and the liquid which determines whether the two soft particles repel or attract. We call the effect the frozen Cheerios effect.Finally, we identified a freezing-induced topological transition of a double-emulsion, i.e., an oil droplet with an immersed water droplet inside, and as a whole immersed in water, passing through a freezing front. Whether the water droplet inside the oil droplet survives or whether it literally bursts due to pressure forces emerging at solidification depends on the control parameters, in particular the freezing front velocity.This is joint work with Jochem Meijer, Pallav Kant, Vincent Bertin, and Duco van Buuren, all Physic of Fluids group, University of Twente.
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https://cassyni.com/events/KyUbz2S8Bv949NmYhrySEy
Chair holder, Physics of Fluids, University of Twente
Detlef Lohse (1963, Hamburg) studied in Kiel and Bonn and did his PhD at the University of Marburg. His PhD thesis, in 1992, was about fully developed turbulence. He then was postdoc at the University of Chicago. His ‘Habilitation’ in 1997 was about sonoluminescence. He joined the University of Twente in 1998 as a Full Professor of Physics of Fluids. Lohse received many prizes, like the Max Planck Medal, the Balzan Prize, the George Batchelor Prize, the Fluid Dynamics Prize of the American Physical Society, the Dutch ‘Simon Stevin Meester’ and the Spinoza Prize. He is a member of the Royal Netherlands Academy of Arts and Sciences (KNAW), the German Academy of Sciences ‘Leopoldina’ and of the American National Academy of Engineering. He is Fellow of the Institute of Physics and of the American Physical Society. He initiated the on-campus ‘Max Planck – University of Twente Center for Complex Fluid Dynamics’, collaborating with two of the prestigious Max Planck Institutes – in Göttingen and Mainz. Detlef Lohse is Distinghuished Professor (‘Universiteitshoogleraar’) of the University of Twente and he was knighted by the Dutch Queen: Ridder in de Orde van de Nederlandse Leeuw.
Journal of Fluid Mechanics
Flow: Applications of Fluid Mechanics
Leeds Institute for Fluid Dynamics
Department of Applied Mathematics and Theoretical Physics
UK Fluids Network
*本文由剑桥大学出版社北京办公室编译，中文内容仅供参考，请以原文为准。如需转载，请联系FLM_Flow@cambridge.org。
