Numerical Simulation of the Disintegration of an Aqueous Drop Under Electric Field

Electrocoalescence is an industrial application of high voltage for separating an aqueous phase from an oil phase using electric field to promote the aggregation of aqueous drops. The thickness of the oil film between drops decreases and ruptures. As a consequence, the drops coalesce together. However, if the electric field is too high, the resultant drop deforms and disintegrates, reducing the efficiency of the electrocoalescence process. In this work, a multiple-physic simulation is performed to determine the critical electric field that causes the disintegration of an aqueous drop. The configuration is an aqueous drop, located on a grounded electrode in an insulating oil under an electric field. We numerically analyze the deformation and disintegration of a drop under the applied electric field using the finite element method. We use the level set method to track the interface between the aqueous drop and the insulating oil. The results show that the aqueous drop elongates due to the electric force and starts to deform under 0.36 kV/mm electric field. The elongation and the deformation of drop increase with the electric field. Eventually, the aqueous drop completely loses its stability at the critical field value, which is equal to 0.9 kV/mm. An experiment is conducted to observe the disintegration of drop. The experimental results demonstrate that the drop disintegration occurs at the average electric field of 1.02 kV/mm, slightly higher than the critical field obtained from the simulation.