Dynamics of entrapped air bubble during impact of high-velocity molten droplet on a solid substrate
In the present study, a numerical model has been developed to investigate the dynamics of the air bubble which has been formed during the high-speed impact of a molten droplet on the cold substrate. In the model impact, spreading and solidification of a molten droplet on a flat surface including the effect of the surrounding air have been considered. The volume of fluid surface tracking method (VOF) coupled with the solidification model within a one-domain continuum formulation is utilized to model the transient flow during the droplet impact. Model completely captured the air bubble formed. It is found that initially a thin circular film of air was trapped at the centre of the droplet which further grew into a large air bubble that eventually breaking through the upper surface of the droplet and creates a hole in the centre portion.