MULTIPHASE MODELING OF DROPLET-BASED 3D PRINTING: PREDICTING PRINTABILITY, RESOLUTION AND SHAPE FIDELITY IN ADDITIVE MANUFACTURING PROCESSES

The multi-phase flow during the evolution of droplets in the printing process is modeled using the Volume of Fluid (VOF) method. It involves solving basic Navier-Stokes and Continuity equations for an incompressible flow with two or more immiscible phases on a finite volume grid. An indicator function keeps track of the interfaces and calculates the surface tension forces. A grid independence study showed convergence, indicating the efficacy of the solutions. The computational model agreed well with the experimental data and captured the impact, spreading, and recoiling of the droplet impinging on a solid surface. The computational model also validated the droplet's interaction with hydrophilic surface for constant and dynamic contact angles. Relevant non-dimensional numbers (Re, We, Oh) are also considered to study the interplay of different forces associated with droplet impact on a solid surface. The final quality of the printing depends on the droplet dynamics associated with the deposition. This phenomenon is governed by body forces (Surface Tension, gravity), contact angle, dissipative forces due to motion, and material properties. Computational studies give an insight into the overall process performance and the final print quality for different process conditions and material properties.