Molecular dynamics study of the impact of a solid drop on a solid target

Abstract

The impact of a drop on a surface can result in bouncing, bonding, or erosion of the drop and the target. The occurrence of these processes is important in many industrial applications such as cold-spray. An experiment indicates that erosion is preceded by jet formation, which is closely related to the bonding/erosion boundary, but a detailed description accounting for jet fragmentation is still lacking. We propose in this article to combine the theoretical analysis and molecular dynamics simulations to explore these complex processes. In a previous article [L. Soulard et al., J. Appl. Phys. 129, 205104 (2021)], we analyzed the simplest case: a drop of liquid on a rigid surface. In this article, we address a more complex case: a solid drop and a solid surface. A detailed analysis of the impact processes allows us to establish simple formulas to calculate the velocity and orientation of the jet and to propose criteria for the appearance of the jet. These theoretical results are then evaluated by comparison to large-scale molecular dynamics simulations. The agreement is partially satisfactory and gives the limits of the theory. The results make it possible to specify the criteria of formation of the jet used in the literature.