Bubble deformation and breakup in a non-uniform electric field

In this paper, the deformation and breakup characteristics of bubbles during their growth in a mixture solution were studied with a needle-ring electrode configuration in the presence of an electric field by using high-speed photography. Four distinct bubble breakup behaviors of the dripping, cone, kink and branch regimes were achieved successfully by manipulating the electric field. By considering the applied voltage and gas flow rate, the cone structure, interface stability, departure frequency and bubble size distribution in different regimes were quantitatively discussed. It is found that the cone height, interface curvature, departure frequency and bubble size distribution are evidently associated with bubble breakup regimes. As the electric field strength increased, the bubbles stretched in the direction of the electric field and the instability of the gas-liquid interface became stronger, which eventually resulted in the bubbles fragmenting into a cluster of microbubbles. This work provides a fundamental understanding of bubble deformation and breakup mechanisms under the electric field.