Dynamics of drop formation from submerged orifices under the influence of electric field

Abstract

We present numerical investigation on the dynamics of drop formation from submerged orifices under the influence of an external electric field. The study is carried out by solving axisymmetric electro-hydrodynamic equations, and the interface is captured using a volume-of-fluid approach. The study reveals that under the influence of an electric field, prolate shaped drops are formed at the orifice in the case of perfect dielectric fluids. The applied electric field strength and the ratio of the dielectric permittivity of the fluids play a pivotal role in deciding the magnitude of deformation as well as volume of the drops. The local electric field intensity inside the drop is significantly altered due to the permittivity contrast between the fluids. The computations for leaky dielectric fluids reveal that both prolate and oblate shaped drops can be formed depending on the combination of the fluid conductivity and permittivity ratios. The breakup time and detached drop volume can be suitably tuned by varying the strength of the applied electric field. The nature of charge accumulation and the electric forces acting at the interface are critically dependent on the relative contrast between the electric properties of both the phases. The fluid flows in a circulatory motion inside the drop, and the flow behavior is decided by the combination of the electrical conductivity and permittivity ratios of the fluids under the influence of the applied electric field.