Instability of non-Newtonian jets with a surface tension gradient

In this paper we investigate the mechanisms of temporal instability of non-Newtonian liquid jets, more specifically viscoelastic liquid jets, with a surface tension gradient. The dispersion relation between the growth rate and the wave number for a viscoelastic liquid jet is derived. The effects of various parameters on the instability behavior are studied. A number of quantitative conclusions and sensitivities on the instability behavior of viscoelastic jets are investigated. The present work can provide a good foundation for further investigations of the instability and breakup of viscoelastic liquid jets in the situation where the surface tension gradient exists. The applications of such a phenomenon include a microfluidic inkjet printheads with thousands of nozzles that are thermally modulated near the nozzle orifice to produce steady steams of picoliter-sized droplets at kilo-Hertz frequency rates.