ON THE SEPARATION OF DROPLETS FROM A LIQUID JET

The droplet separation from a liquid jet was investigated experimental ly. Details of the shape of the thin liquid neck joining the droplet t o its parent body were studied in terms of the fluid viscosity and the jet diameter. As the viscosity increased, the neck rapidly elongated creating a long thread. Its final diameter before rupture was approxim ately one micrometer and seems to be constant within wide range of par ameters varied. One or multiple breakups of the micro-thread were obse rved, which produced micro-satellites, i.e. droplets in a micrometer r ange. The experimental results only partly confirmed the predictions o f Eggers' (Phys. Rev. Lett. 71 (1993) 3458) similarity solution. The p redicted shape of the pinch-off region well overlaps the long thread o bserved for very viscous liquids. However, the final jet diameter, ret raction velocity of the thread and presence of multiple breakups diffe rentiate the experimental evidence from the model expectations.