Analysis and Computational Modelling of Drop Formation for Piezo-Actuated DOD Micro-Dispenser

Abstract

Drop-on-demand micro-dispenser has been dramatically used in inkjet printing rapid prototyping applications. To predict the drop size, its velocity and shape evolution, it is necessary to understand the drop formation process. In this thesis, an analytical method is used to analyze the oscillatory fluid movement inside a squeezed-type piezoelectric cylindrical inkjet print head with tapered nozzle. In this thesis, a two-dimensional axisymmetric numerical simulation model of the drop formation from the nozzle has been developed with the Volume-of-Fluid (VOF) method and the Piecewise-Linear Interface Calculation (PLIC) technique. The driving signal applied to the piezo-actuated capillary is simulated via a Fluent-C program by using the User Defined Function (UDF) of FLUENT. The thesis presents a detailed description of the three main stages during the drop ejection process, and discusses the effect of the Reynolds number and Capillary number on the dynamics of drop formation.