Experimental and Numerical Analysis of Filament Front Deformation for Direct-Print

The purpose of this research is to perform an investigation of continuously dispensed material (or filament) deformation during dispensing. Depending on the material properties, and the process parameters the deformation behavior of the filament changes, so as the formation of the filament front (the front face of the filament, i.e., dispensing material). The focus of this investigation is the study of the evolution of the filament shape for Newtonian fluid experimentally and computationally. The experimental analysis has been performed with commercially available monomers with the help of a screw driven micro dispensing system installed on a high precision xyz translation stage. The imaging system consists of a high resolution CMOS camera. The developed computational model utilizes an adaptive quadtree spatial discretization with piecewise–linear geometrical volume–of–fluid (VOF) method for calculating the volume fraction for this multiphase problem. The model employs the continuum–surface–force model for formulating the surface tension, whereas the height function (HF) to estimate the curvature for tracking the evolution of the filament shape during the deformation. The computational model has been developed using an open source solver, Gerris Flow Solver. The considered governing and process parameters for this investigation are Froude number (Fr), Reynolds number (Re), gap ratio (GR), and velocity ratio (VR). The VR is the ratio of travel velocity to dispensing velocity. The GR is the ratio of filament height to filament diameter. Results have been presented as the interface contour for the filament front. The investigation shows that the results found from the developed model have a good agreement with experimental results, and the deformation phenomena is greatly influenced by the variation of the governing parameters.