title: Shrinking instability of toroidal droplets.
abstract: Toroidal droplets are inherently unstable due to surface tension. They can break up, similar to cylindrical jets, but also exhibit a shrinking instability, which is inherent to the toroidal shape. We investigate the evolution of shrinking toroidal droplets using particle image velocimetry. We obtain the flow field inside the droplets and show that as the torus evolves, its cross-section significantly deviates from circular. We then use the experimentally obtained velocities at the torus interface to theoretically reconstruct the internal flow field. Our calculation correctly describes the experimental results and elucidates the role of those modes that, among the many possible ones, are required to capture all of the relevant experimental features.
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430.
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Fragkopoulos
authors.affiliation: Department of Food Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
authors.forename: Ekapop
authors.initials: E
authors.lastname: Pairam
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430.
authors.forename: Eric
authors.initials: E
authors.lastname: Berger
authors.affiliation: Oxford College, Emory University, Oxford, GA 30054.
authors.forename: Phil N
authors.initials: PN
authors.lastname: Segre
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430; alberto.fernandez@physics.gatech.edu.
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernández-Nieves
keywords: PIV; Stokes flow; hydrodynamic instabilities; liquid tori; stream function