Stability analysis of a drop in a pin-to-plate electrohydrostatic system

Stability of a drop in a pin to plate electrohydrostatic system was examined both theoretically and experimentally. With this static model, the mechanism of electrostatic ink jetting process was estimated. The basic equations are the augmented Young-Laplace equation for drop shape and the Laplace equation for electric field. These coupled equations were solved by the Finite Element Method. By the initial condition of its shape, a drop could be deformed into anomalous shapes, such as "nipple" and "dog bone," as well as conical shape, often referred as Taylor cone with the increment of non dimensional electric field. The concentration of electric field around the corner of a nozzle was the cause of these anomalous shapes. By this stability nnalsis, it was demonstrated that the electrostatic ink jetting modes, dripping mode and the onset of cone jet mode, were governed by the force balance between forces from surface tension, pressure and electrostatic field.