Non-linear vibration of a water drop subjected to high-voltage pulsed electric field in oil: Estimation of stretching deformation and resonance frequency

A drop of water subjected to a pulsed electric field in emulsified oil undergoes periodic stretching vibration, which is very effective for promoting the coalescence of the emulsified drops. In this study, the forces that act on a single water drop during its vibration in a pulsed electric field are analysed, and a dynamics model of the vibration of the drop is developed. The expression of the model indicates that the vibration can be described as a non-linear parametric excitation vibration, and comparison of the model predictions with experimental results reveals a good similarity. In addition, a first-order approximation of the predictions of the model is used to obtain the waveforms of the vibration, and the peak of the amplitude–frequency curve reveals the occurrence of resonance. This affords a basis for determining the optimal demulsification frequency of the emulsified oil in the pulsed electric field.