Numerical analysis of post-impact droplet deformation for direct-print

Abstract

Two-dimensional (2D) numerical investigations of droplet impacts on a solid surface and the consequent deformation have been performed. The application lies in the direct-print technology where droplets are used to create lines and instantly cured to maintain line dimension. The investigation focuses on the evolution of droplet shape at the initial stage after the impact for Newtonian fluids. More specifically, the investigation emphasized the time for an impacted droplet to start increasing its diameter after the initial compression due to impact. A computational model has been developed by utilizing an adaptive quadtree spatial discretization with piecewise-linear geometrical volume-of-fluid (VOF) for this multiphase problem. The continuum-surface-force method and the height-function (HF) were employed for estimating the surface tension and the interface curvature, respectively. The Gerris Flow Solver, an open-source finite-volume package, was used for developing the computational model. The investigation was performed for the governing parameters of the Froude number (Fr), Reynolds number (Re), and Weber number (We). The results are presented as the interface contour, spreading factor (ξ), and deformation ratio (Rδ). The investigation shows that the results from the developed model have excellent agreement with the experimental results.