Flow state transition and hydrodynamic characteristics of droplets on fiber in liquid phase environment

Abstract

The movement of droplets on fiber is crucial for industrial applications. In this work, the motion behavior and flow state transformation mechanism of droplets on vertical fiber in liquid phase environment is systematically investigated by using image processing technology. The effect of different factors on the hydrodynamic characteristics is analyzed during the droplet movement process. The experimental results show that the three flow states are observed during the flow of droplets along the fiber in liquid phase environment, including stable state, oscillation state, and coalescence state. Among them, the transverse oscillation of the droplets has a certain periodicity, and the primary coalescence rate of the droplets is 16.22% faster than secondary coalescence. Increasing the fiber diameter can expand the flow rate range of droplets in the stable state and significantly enhance the critical flow rate. Moreover, with the increase of nozzle diameter, the flow rate range of the oscillation state is increased and the flow rate range of the coalescence state is decreased. During the stable state, the hydrodynamic characteristics of droplets are influenced by factors such as fiber diameter, nozzle diameter, and flow rate. The study results not only contribute to deeply understand the movement mechanism of droplets on fiber surface, but also have an important significance in promoting the development of liquid–liquid extraction technology and droplet microfluidics technology.