Deformation and breakup of double emulsion droplets under an electric field by lattice Boltzmann simulation

Double-emulsion droplets subjected to electric fields are widely used in chemical, petroleum, and food-processing applications, yet the mechanisms governing their deformation and breakup are not well understood. In this work, a multi-component lattice Boltzmann method coupled with the leaky dielectric model is employed to investigate the electrohydrodynamic behavior of stationary component-a-in-component-b-in-component-a (a/b/a) compound droplets over a representative range of dielectric constant and electrical conductivity ratios. Four distinct breakup modes are identified, governed by the relative prolate–oblate responses of the inner and outer droplets. Droplets exhibiting asymmetric deformation are more susceptible to rupture than those undergoing symmetric deformation. In particular, breakup dominated by outer-droplet elongation requires a stronger electric field than that driven by inner-droplet elongation. At sufficiently high electric field strengths, concave deformation of the inner droplet promotes multi-fragment breakup of the outer droplet. These results provide physical insight into electric field-induced breakup in double emulsions and offer guidance for the design and control of droplet-based electrohydrodynamic processes.