ABSTRACT

When a solid object starts falling into a viscous fluid from air-liquid interface, air is entrained into the liquid and eventually detaches from the solid. Such detachment could occur with or without topological change. Recently, it was found that the former case (i.e., breakup, a form of singular transitions) is observed in a confined geometry but the topology change is suppressed in a more confined geometry, by falling a metal disk in a vertically stood Hele-Shaw cell filled with a viscous liquid with the disk axis perpendicular to the direction of gravity. In this talk, we discuss the results when we tune a confinement parameter, the thickness difference between the cell and the disk, with fixing another confinement parameter, the disk thickness. As a result, we find that the present hydrodynamic case possesses a strikingly close analogy with critical phenomena. Critical phenomena have widely been observed in nature, and the concept of universality class, which has emerged from our understanding of critical phenomena, has guided the recent development of physics. Accordingly, identifying a rich variety of universality class is a major issue in modern physics. Here, we remarkably find the present hydrodynamic analog of critical phenomena reveals the existence of an uncountably infinite number of universality classes, by showing critical exponents that define a universality class depend on continuous numbers characterizing the confinement.

BRIEF ACADEMIC/EMPLOYMENT HISTORY:

During his graduate study, he performed research in various topics in theoretical physics, including quantum field theory (particle physics), supersymmetry, nonequilibrium statistical mechanics, electron systems etc, to produce 8 academic papers. After becoming research associate, he made a significant contribution to molecular vibration spectroscopy by bringing in field-theoretical techniques to the field of molecular science. Furthermore, he started working on the toughness of pearl (nacre) with a Novel prized physicist, de Gennes, in Paris. There, he was deeply impressed by the spirit of impressionistic physics, which allows us to extract simple physical essences form complex real-world phenomena. As a result, he shifted his field towards soft matter physics and has explored in the field statistical physics viewpoints such as scaling in critical phenomena. His current interests include fracture and toughness of soft-hard complex, wetting and thin film dynamics, granular systems, and so forth.  REM: I was a visiting phD student in high-energy physics group of CUNY
(supervisor: late Bunji Sakita) from 1991 to 1992.