Absolute Instability of a Liquid Jet in a Coflowing Stream

Abstract

Cylindrical liquid jets are inherently unstable and eventually break into drops due to the Rayleigh-Plateau instability, characterized by the growth of disturbances that are either convective or absolute in nature. Convective instabilities grow in amplitude as they are swept along by the flow, while absolute instabilities are disturbances that grow at a fixed spatial location. Liquid jets are nearly always convectively unstable. Here we show that two-phase jets can breakup due to an absolute instability that depends on the capillary number of the outer liquid, provided the Weber number of the inner liquid is >O(1). We verify our experimental observations with a linear stability analysis.

Dynamics of microfluidic droplets

“…among others. More recently, Utada et al 20 have generalized these results by relaxing first the lubrication assumption and then the creeping flow limit, thus considering inertial effects that become significant at large capillary numbers.…”

Nonlinear Instability and Breakup of a Viscous Compound Liquid Jet

“…Furthermore, it is known that an abrupt change of breakup length in the column jet appears at a transition between two different flow regimes (such as dripping and jetting), whose regimes are corresponding to the absolute and convective instabilities (9), (10) . It is then expected in the present analysis that the Weber number at which the abrupt change of z b appears in Fig.3(c) is just the critical Weber number Wb c , which is Wb c = 10 for φ = π and 2.4 for 0 from Fig.3(c).…”

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“…Coaxial glass capillary devices have been used for making emulsions [12], microparticles [13], and giant vesicles [9]; however, so far, these devices…”