Coalescence of Al droplet impacting on a melt surface

The droplet falling into its bulk liquid surface is very common but complex which widely exists in nature and industry. In this case, the impact behavior is almost simultaneous with the coalescence. To deeply understand the dynamics and mechanism of this phenomenon, molecular dynamics simulations have been performed to study the characteristics of the impact coalescence process under different conditions. Results show that four coalescence behaviors, including rebound, calm coalescence, deformation and coating, are mainly determined by the impact velocity. Interestingly, a cavity is observed in the liquid bulk when the impact velocity is big enough, which can be explained by the momentum transfer. Beyond that, the mixing degree increases with Weber number and there is a critical Weber number between rebound and coalescence. The study illustrates how the temperature and impact velocity affects the coalescence behavior and provides opportunity to well understand the droplet impact process towards its melt surface.

Automated summary

The impact behavior of a droplet falling into its bulk liquid surface is determined by the impact velocity, leading to various coalescence behaviors such as rebound, calm coalescence, deformation, and coating. Molecular dynamics simulations have shown that a cavity can form in the liquid bulk at high impact velocities due to momentum transfer. As the Weber number increases, the degree of mixing also increases, with a critical Weber number separating rebound and coalescence behaviors. The study provides insights into how temperature and impact velocity influence droplet coalescence behavior.