NUMERICAL SIMULATION ON BUBBLE RINSING BEHAVIORS UNDER ELECTRIC FIELD

Employing an electric field to control bubble morphology and motion, and enhance heat and mass transfer between gas and liquid are one of the important research contents of electrohydrodynamics (EHD). However, most of the current researches focus on the dynamics of bubbles under non-electric fields. Further research is needed on the behaviors of bubbles and the mechanism of electric fields under electric fields. In the present study, the dynamic behaviors of a single bubble rising in a fluid under an external electric field are numerically simulated. Based on the model established on two-dimensional, the equation of electric field and Navier-Stokes are solved, and the level set method is used to accurately capture the position and morphology of the rising bubble. The accuracy and validity of the present simulation results are verified by comparing with previous experiments and numerical results. The effects of liquid viscosity, surface tension and electric field force on bubble motion and deformation under electric field are examined by employing the Reynolds (Re), Bond (Bo) and electrical bond (Bo_\rm e) numbers. The calculation results show that the electric field has a significant influence on the dynamic characteristics of the bubble. In the case of a non-electric field, the bubble basically maintains a spherical shape when the viscosity of the liquid and the surface tension are large. Instead, the bubbles deform and gradually reach a steady state. Additionally, the bubble is strongly deformed at the initial rising stage by attributing to the electric field. With the bubble further rising, the deformation weakened, and both of the bubble velocity and aspect ratio are oscillated. The effect of vertical electric field causes a greater increase in the velocity of rising bubble. As the number of Bo_\rm e increases, the bubble has an intense oscillation, making it more difficult to achieve a relatively stable state.