Numerical Simulation on Movement Behavior of Air Bubbles in Viscous Fluid

Abstract

Listen

Translate article

The computational geometry models of one bubble and two bubbles in viscous fluid were built. The Volume of Fluid model and pressure-velocity coupling solution method are used to solve the movement equation of air bubbles to investigate the movement, coalescence, and collapse of air bubbles. The results show at the beginning, the shape of the air bubble changes to ellipse from circle. The velocity of the air bubble greatly increases when the air bubble collapses; in the meanwhile the jet flow is produced. After the bubble collapses, the velocity of the oil decreases gradually. The movement velocity of two air bubbles is greater than that of one bubble. Introduction Hydro-viscous drive (HVD) theory applied to high-power mechanical equipment for speed regulation and soft start, has obvious energy-saving effects, which transmits power using viscosity of fluid [1]. This research field has been attracting many scholars from all over the world. Par Marklund et al. [2, 3] studied torque, friction and lubrication of one pair of friction pair under the condition of boundary lubrication, and also made some experimental verification. Hong et al. [4] built mean surface roughness model and GT contact model, and proposed a calculation method for output rotation speed and torque under stable condition. Xie et al. [5, 6] built a revised Navier-Stokes equation based on the viscosity-temperature relationship, and investigated the effect of temperature, grooves, and deformed interface on capacity and torque of the oil film. All of above scholars suppose the viscous fluid is single phase oil film. However, we found the air bubbles in the oil film will affect the transmission characteristics of the HVD. In this paper, the Volume of Fluid (VOF) model and pressure-velocity coupling solution method are used to solve the movement equation of air bubbles to trace the gas-fluid interface. Then, the movement, coalescence, and collapse of air bubbles in the viscous fluid are investigated in this paper.