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 (R δ ). The investigation shows that the results from the developed model have excellent agreement with the experimental results.

Control of Drop Impact and Proposal of Pseudo-superhydrophobicity Using Electrostatics

“…Their numerical model predicted the scaling laws for rim diameter and the transient boundary layer thickness during spreading. The numerical investigation of Hasan et al 12 provides the influence of the different parameters like Weber number, Reynolds number, and Froude number on droplet deformation after the impact. Philippi et al 13 performed numerical simulations to analyze the early stages of droplet impact on a solid surface.…”

“…Thus, the collision behavior of a droplet has become a topic of fundamental importance for comprehension of its applicability in different engineering scenarios. Both experimental ,− and numerical − investigations have been performed to analyze the phenomenon of droplet impact. The experimental study of Rioboo et al shows that for different parameters, like viscosity, drop diameter, surface roughness, and wetting nature, similarity of spreading pattern exists at early stages of the impact only, whereas the influencing factors dominate at the later stages.…”