2026-01-13 ニューヨーク大学（NYU）
Two spinners inside a circular container and surrounded by liquid with bubbles that help to visualize the flows. The left spinner is actively driven to rotate with a motor (not shown) and the right one passively rotates due to the flows. Image courtesy of NYU’s Applied Mathematics Laboratory
＜関連情報＞
- https://www.nyu.edu/about/news-publications/news/2026/january/scientists-put-teeth-into-water-driven-gears.html
- https://journals.aps.org/prl/abstract/10.1103/m6ft-ll2c
回転子の流体力学的スピン結合 Hydrodynamic Spin-Coupling of Rotors
Jesse Etan Smith, Leif Ristroph, and Jun Zhang
Physical Review Letters Published: 13 January, 2026
DOI:DOI: https://doi.org/10.1103/m6ft-ll2c
Abstract
Flow-mediated interactions between objects are important in sedimentation and collective locomotion. New phenomena arise in systems that are dominantly coupled by rotation, as relevant to active matter physics and biological and engineering contexts. Here we establish an experimental platform for studying fluid mechanical spin-coupling effects and map out how interactions depend on proximity, confinement, and flow state. The two-body problem of a driven rotor inducing spin of a passive rotor reveals a gearlike counterrotation mode but also surprising corotation modes that occur broadly across the parameter space. Streamline analysis and a mechanical model indicate distinct transitions between modes that arise geometrically at close range, topologically due to flow reconfiguration, and inertially with increasing Reynolds number. These findings provide ways to understand, control, and exploit hydrodynamic spin-spin interactions in applications.
