A multiphysics model for analysis of droplet formation in electrohydrodynamic 3D printing process

Electrohydrodynamic (EHD) printing is a novel technology used for fabricating high-resolution part features from a wide range of materials. Due to the multiphysics dynamics and the multiphase nature of the microdroplet formation in the EHD printers, modeling of this phenomenon is complicated. In this paper, the formation of a droplet in an EHD printer-under a pulsed electrical field-is simulated using a new numerical model which couples the fluid flow, the electric field distribution and the movement of the electric charges under dynamic and transient conditions. The level-set method is applied to the entire multiphysics domain in order to study the formation of the droplet. The presented model is verified by comparing to the existing experimental results in the literature. In order to find the effective parameters with significant impact, at 95% confidence level, a sensitivity analysis of the process parameters is carried out based on the Plackett-Burman design of experiment approach. It is found that the voltage, the permittivity of ink, the nozzle height above substrate, the density and the conductivity of ink are the most effective parameters.