Formation of a drop: viscosity dependence of three flow regimes

Abstract

We observe the drop pinch-off at a nozzle for different viscosities and investigate three consecutive flow types. In its first stage the neck of the drop shrinks in an accelerated manner similar to the instability of a liquid cylinder. In the vicinity of the pinch point the motion becomes self-similar at a certain time. The self-similar domain consists of two flow regimes separated by a second transition point. The viscosity dependence of the transition points can be described by linear functions. Moreover, it is uncovered that both transitions occur when two different critical neck radii are reached. These radii are found to be independent of viscosity.