Numerical study of continuous liquid tin jet breakup and satellite droplet formation

This study proposed a velocity modulation model in which the main flow and perturbation were defined as velocity inlet boundary conditions to simulate liquid tin jet breakup into droplets with external disturbances. The volume of the fluid method was implemented for interface tracking, and adaptive mesh refinement was adopted to guarantee the accuracy of perturbation evolution at the interface during numerical iterations. When the dimensionless wave number is 0.7, almost no satellite droplets are formed. However, when the dimensionless wave number decreases to 0.51, satellite droplets are generated evidently and exhibit from backward-merging to forward-merging with the primary droplets as the disturbance amplitude increases. From the velocity profile, the jet evolution can be divided into three regions: non-breakup, droplet streams, and breakup-merging regime. The droplet sequence uniformity is poor with a small disturbance amplitude. Compared with the conventional velocity modulation model, the proposed model can describe the transition of satellite droplets from backward-merging to forward-merging with increased disturbance amplitude. If the dimensionless wave number is higher than 0.3, only forward-merging occurs with large disturbance amplitudes. Furthermore, in the condition that the dimensionless wave number decreases to 0.25 and below, satellite droplets merge forward and backward simultaneously. Increasing the disturbance amplitude makes the mergence of satellite droplets with the main droplet significantly faster when the dimensionless wave number is 0.3 or below. On the contrary, if the dimensionless wave number is more significant than 0.38, the mergence of satellite droplets slows down with the increase in the disturbance amplitude.