title: Whipping of electrified liquid jets.
abstract: We apply an electric field to a moderately conducting liquid surrounded by another coflowing liquid, all inside a glass-based microfluidic device, to study nonaxisymmetric instabilities. We find that the bending of the electrified jet results in a steady-state, helicoidal structure with a constant opening angle. Remarkably, the characteristic phase speed of the helicoidal wave only depends on the charge carried by the jet in the helicoidal region and its stability critically depends on the properties of the coflowing liquid. In fact, the steady-state helical structure becomes chaotic when the longest characteristic time is that of the inner liquid rather than that of the outer coflowing liquid. We also perform a numerical analysis to show that the natural preference of the jet is to adopt the conical helix structure observed experimentally.
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332; and.
authors.forename: Josefa
authors.initials: J
authors.lastname: Guerrero
authors.affiliation: Departmento de Ingenieria Aereoespacial y Mecanica de Fluidos, University of Sevilla, Sevilla 41092, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Rivero
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332; and.
authors.forename: Venkata R
authors.initials: VR
authors.lastname: Gundabala
authors.affiliation: Departmento de Ingenieria Aereoespacial y Mecanica de Fluidos, University of Sevilla, Sevilla 41092, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Perez-Saborid
authors.affiliation: School of Physics, Georgia Institute of Technology, Atlanta, GA 30332; and alberto.fernandez@physics.gatech.edu.
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernandez-Nieves
keywords: charged jets; electro-coflow; electrospinning; instability