  This paper describes a lattice Boltzmann-based binary fluid model for inkjet
printing. In this model, a time-dependent driving force is applied to actuate
the droplet ejection. As a result, the actuation can be accurately controlled
by adjusting the intensity and duration of the positive and negative forces, as
well as the idle time. The present model was verified by reproducing the actual
single droplet ejection process captured by fast imaging. This model was
subsequently used to investigate droplet formation in piezoelectric inkjet
printing. It was determined that wettability of the nozzle inner wall and the
surface tension of the ink are vital factors controlling the print quality and
speed. Increasing the contact angle of the nozzle inner delays the droplet
breakup time and reduces the droplet velocity. In contrast, higher surface
tension values promote earlier droplet breakup and faster drop velocity. These
results indicate that the hydrophilic modification of the nozzle inner wall and
the choice of inks with high surface tensions will improve printing quality.
