Understanding the breakup mechanism of a droplet under a DC electric field with molecular dynamics simulations and weak interaction analysis

Abstract

Electrical dispersion of a water-in-oil emulsion under an electric field has an inhibitory effect on the eletrocoalescence. To clarify the mechanism of droplet breakup at the microscopic level, molecular dynamics simulation was performed to study the deformation and breakup characteristics of a moving droplet at different field strengths. The results showed that interparticle spacings increased with the growth of the field strength, leading to significantly higher values of the electrostatic potential and van der Waals potential, and hence an increase of the deformation degree. There was a substantial rise in the non-bonded potential energy with a sharp fall in the overall velocity of the droplet when the electric field was higher than 2.1 V nm−1, causing the development of droplet breakup. Through hydrogen bond and hydration analysis, it was found that the hydrogen bond lifetime and ion distribution were responsible for the formation of different breakup patterns. These results demonstrated that droplet break-up is highly dependent on weak intermolecular interactions such as strong attraction.