Reference: Physical Review Letters
123, 094502 (2019) 
URL: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.094502
Abstract: We report the first
quantitative measurements of the resonance frequencies of a
torus of fluid confined in a horizontal Hele-Shaw cell. By using
the unwetting property of a metal liquid, we are able to
generate a stable torus of fluid with an arbitrary aspect ratio.
When subjected to vibrations, the torus displays azimuthal
patterns at its outer periphery. These lobes oscillate radially,
and their number n depends on the forcing frequency. We
report the instability ``tongues'' of the patterns up to n=25.
These resonance frequencies are well explained by adapting to a
fluid torus the usual drop model of Lord Rayleigh. This approach
could be applied to the modeling of large-scale structures
arisen transiently in vortex rings in various domains.
"The first observation od a stable torus of
fluid's resonance frequencies" Phys.Org, 13
September 2019 by I. Fadelli (Article
in PDF)
CNRS Research News
"Stabilization of a fluid ring",
14 October 2019, by Martin Koppe (in french) in
CNRS
Lettre "En direct des labos" 15 October
2019, Tweeter_@INSIS_CNRS
16 Oct. 2019
"How to make a fluid ring
stable?", University of Paris Web Site, 6
Sept. 2019 (in french)
"Observation de modes stables d'un tore de
fluide", MSC Laboratory Web Site, 17
Oct. 2019 (in french)
