Computational fluid dynamics analysis of a direct write manufacturing process

Abstract

This paper investigates the microdroplet generation mechanism in a direct write manufacturing process. A continuous inkjet (CIJ) method is utilised to deposit conductive nano particulate materials which can be used for building functionally gradient micro-sized features and devices. The spatial and temporal complexity of this process requires a computational modelling methodology to complement its experimental development. A CFD model is developed that is further validated using an ultra-high speed photography experimental setup. Input parameters such as fluid pressure, excitation frequency and voltage of the piezoelectric disc within the CIJ print head are varied to obtain trends for droplet volume and velocity. The dynamic pressure fluctuations due to acoustic waves generated during the piezoelectric disc excitation are studied. The effect of excitation parameters on satellite droplet formations is explained. These findings can be useful for the fabrication of freeform miniaturised devices in three dimensional spaces.