Lattice Boltzmann simulation of droplet dynamics in binder jet three-dimensional printing

In this paper, the dynamic behavior of droplets impacting and penetrating a three-dimensional (3D) circular particle bed in binder jet 3D printing is numerically simulated using the lattice Boltzmann method, and the influence of particle bed pore structure and binder droplet parameters on the dynamics of droplet impact and penetration is explored. A color-gradient model is established to simulate two-phase flows with a high density ratio between the binder and air. Based on this model, the influence of pore characteristics on droplet dynamics is investigated by constructing body-centered cubic particle beds with two different particle sizes and irregular beds. Moreover, the effect of droplet impact velocity on these dynamics is also examined. The computational results indicate that the small-sized particle facilitates droplet spreading due to enhanced capillary effect, whereas the large-sized particle enables deep penetration due to its low resistance properties for the body-centered particle bed situation. High-velocity impacts exhibit greater penetration efficiency in larger pores, whereas low-velocity conditions achieve faster capillary penetration in smaller pore systems. Furthermore, in an irregular particle bed, different droplet impact velocity conditions lead to significant partitioning effects, with the velocity magnitude influencing the displacement of droplets. This study provides a theoretical foundation for optimizing binder droplet impact and penetration parameters in binder jet 3D printing, thereby enhancing the precision and quality of the printing process.