Liquid pinching dynamics in an inertial transitioning regime

The pinching of a liquid filament at low viscosity, whether in air or liquid, shows a rich and interesting behavior. The liquid thread thins according to a capillary-inertial regime power law at the beginning, before transitioning into other regimes when approaching the pinching moment. Here we study the pinching of a pendant drop revealing the effect of internal and external viscosity on thread thinning. We show an inertial transitioning regime in which slower thinning happens by slightly increasing not only the droplet viscosity but also the viscosity of the surrounding liquid. The viscosity is found to reduce the filament neck axial velocity leading to a slower thinning. We derive a simple universal scaling law that can predict the thinning inertial prefactor value as a function of the neck axial velocity showing excellent agreement with numerical data. Finally, the breakup of satellite droplets is characterized given the defined thinning regimes. Published by the American Physical Society 2024