Electrocoalescence of two charged nanodroplets under different types of external electric fields

Droplet coalescence induced by an external electric field has been extensively applied in industries. However, the coalescence dynamics of droplets under three common types of electric fields, direct current (DC), alternative current (AC), and pulsed DC electric fields, and the corresponding coalescence mechanisms are unsatisfactorily explored. This study applied molecular dynamic simulations to investigate the coalescence dynamics of two charged droplets under these three types of electric fields. At the same field strengths, the contact time by applying the DC electric field is noted as the shortest among the three studied electric fields, and this is followed by the AC and the pulsed DC electric field. The DC and AC electric fields always possess the same critical field strengths, which are much lower than that of the pulsed DC electric field. The critical field strength is noted to be independent of the period under the AC electric field, whereas would decrease with increasing the period under the pulsed DC electric field. Despite the different dependence of critical field strength on pulse period, interestingly, the critical field strength, E_c, under the pulsed DC electric field is approximately equal to that under the AC electric field at a long period limit; conversely, the critical root-mean-square (RMS) field strength, E_RMS,c, under the pulsed DC electric field is close to that under the AC electric fields at a short period limit.