Unconfined liquid filaments are unstable and eventually forms droplets. Although the droplet pinch-off for monodisperse, bidisperse and polydisperse particulate suspensions is well documented, the effect of incorporating microbubbles on liquid thread breakup, and thus droplet formation, is still unknown. Herein, we investigate the pinch-off dynamics of a water-glycerol-surfactant solution in a surrounding oil medium, before and after the addition of microbubbles. We report a difference in the necking dynamics when larger microbubbles are present in the neck, and thus a subsequent effect on the formation of satellite droplets. On the contrary, smaller microbubbles do not have the same effect and leave necking dynamics almost unchanged. We create microbubbles through three methods: vigorous shaking by hand, a bubble nozzle using low pressure air, and sonication. The pinch-off is recorded using a KRÜSS Drop Shape Analyzer and the bubbles are imaged using a Nikon TiE microscope. The methods of shaking and a bubble nozzle create a non-uniform dispersion of larger microbubbles that slightly alter the pinch-off dynamics from that of bubble-free water; while sonication creates a more uniform dispersion of smaller microbubbles that leaves pinch-off virtually unchanged.
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