3D numerical simulation of successive deposition of uniform molten Al droplets on a moving substrate and experimental validation

The deposition of uniform metal droplets has attracted extensive interest for potential application in rapid prototyping and manufacturing. In this paper, a three-dimensional model based on a volume of fluid (VOF) method was developed to investigate the successive deposition of molten Al droplets on a horizontally moving substrate. In this model, protecting gas surrounding the droplets was treated as a void region, and then the droplets were considered as a single-phase fluid. The spreading, cooling and solidification processes of droplets were investigated under different substrate velocities. The simulated final morphology of droplets agreed well with experiments carried out under the same conditions. It was found that the molten Al droplets solidified in a layer by layer mode due to the high heat conductivity. A series of L-shaped ridges appeared on the surface of solidified droplets, which resulted from the integrated effects from solidification and oscillation consisting of alternately spreading and recoiling of droplets.