Three-Dimensional Numerical Simulation of Bubble Dynamics in Microgravity under the Influence of Nonuniform Electric Fields

A three-dimensional VOSET method is used along with the adaptive mesh refinement (AMR) method to simulate the behaviors of a bubble departing from the outside wall of a horizontal square-cross-section tube in microgravity under the influence of nonuniform electric fields. The effects of gravity, electric field intensity, fluid permittivity, and bubble initial position on the bubble detachment and rising are investigated and analyzed. Computational results show that the gravity and electric fields have significant influences on the bubble detachment and rising velocity and rising trajectory. Decrease in gravity results in the decrease in the buoyancy exerted on the bubble, considerably mitigating the rising capability of the bubble and delaying the bubble detachment. Imposing a nonuniform electric field, which exhibits physically the strongest intensity in regions near the tube wall, can supply an additional driving force as a replacement of the buoyancy to accelerate the bubble detachment and rising. It is also shown that a larger electric field intensity or larger ratio of liquid permittivity to gas permittivity leads to a larger deformation, easier detachment, and larger rising velocity, of the bubble. The nonuniformity of the electric fields can also affect the bubble motion trajectory and result in the asymmetric deformation of the bubble.