title: Bubbling in unbounded coflowing liquids.
abstract: An investigation of the stability of low density and viscosity fluid jets and spouts in unbounded coflowing liquids is presented. A full parametrical analysis from low to high Weber and Reynolds numbers shows that the presence of any fluid of finite density and viscosity inside the hollow jet elicits a transition from an absolute to a convective instability at a finite value of the Weber number, for any value of the Reynolds number. Below that critical value of the Weber number, the absolute character of the instability leads to local breakup, and consequently to local bubbling. Experimental data support our model.
authors.affiliation: Escuela Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092 Sevilla, Spain. amgc@us.es
authors.forename: Alfonso M
authors.initials: AM
authors.lastname: Gañán-Calvo
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Herrada
authors.forename: Piotr
authors.initials: P
authors.lastname: Garstecki