Microscopic mechanism on coalescence of the nano-droplets in present non-uniform electric field by molecular dynamics simulations

Abstract

Molecular dynamics simulations are performed to investigate the nano-droplets coalescence process in a non-uniform electric field. Coalescence of droplets driven by dielectrophoresis (DEP) could be observed clearly in a strong electric field. The efficiency of coalescence is remarkably improved about 2 times for non-uniform electric field as much as the efficiency for the uniform electric field. Increasing the gradient of the field, it is found that the DEP force will accelerate the droplets motion of coalescence. But when the gradient of the field increases to a certain degree, the DEP force acting on the droplets presents strongly and rapidly nonlinear increasing and induces the droplets forming the chain structure due to intensively elongating. Moreover, the average operating voltages is much lower in non-uniform electric field.

Effects of Temperature and Ionic Concentration on Nanodroplet Electrocoalescence

“…Commonly, polarization intensity P characterizes the degree of polarization and is calculated by eq where p is the dipole moment vector of the droplet and is obtained by calculating the expression of ∑ i q i r …”

“…where p is the dipole moment vector of the droplet and is obtained by calculating the expression of ∑ i q i r. 28 V is the volume of a droplet. It should be noticed that the droplet volume still maintains its original size after the equilibrium calculation.…”

Energy Component Analysis of Electric Field-Induced Shape Change in Water Nanodroplets

“…Not only is understanding the general behavior of nanodroplets important in fields such as atmosphere and climate modeling, 14 but more specifically, the dynamics of nanoscale water droplets in electric fields is proving to be of interest for applications as diverse as nanoelectromechanical systems 15 and petroleum dewatering. 16 An interesting question in this context is whether a nanosized droplet of discrete water molecules undergoes shape deformation and exhibits instability in externally applied electric fields as Taylor's macromechanical theory predicts. mostly assumed water droplets on a solid surface in the context of electrowetting.…”

“…While experimental and theoretical studies (including those mentioned above) of macro- and microscale water droplets in electric fields have a long history, more recently, advances in technology and science have increased the interest in nanoscale droplets of water. Not only is understanding the general behavior of nanodroplets important in fields such as atmosphere and climate modeling, but more specifically, the dynamics of nanoscale water droplets in electric fields is proving to be of interest for applications as diverse as nanoelectromechanical systems and petroleum dewatering . An interesting question in this context is whether a nanosized droplet of discrete water molecules undergoes shape deformation and exhibits instability in externally applied electric fields as Taylor’s macromechanical theory predicts.…”