The Secondary Bjerknes Force between Two Bubbles in Ultrasonic Field

The aggregation behavior of cavitation bubbles in liquids has vital effect on the ultrasonic cavitation effect. The secondary Bjerknes force between two bubbles is one of the mechanisms underlying this aggregation behavior of bubbles. In this paper, the secondary Bjerknes force between two bubbles, which are irradiated by a high-intensity ultrasonic field (near the Blake threshold), is numerically calculated. In addition, the influences of pressure amplitude, physical parameters, distance between the bubbles and equilibrium radii of bubble-pairs on the secondary Bjerknes force are also investigated. The results show that when the pressure amplitude is greater than Blake threshold, the secondary Bjerknes force between bubbles of equal and unequal equilibrium radii increases markedly with pressure amplitude increasing. The secondary Bjerknes force decreases with the increase of liquid viscosity, surface tension and density, while increases with the saturated vapor pressure increasing. For the two bubbles of larger equilibrium radii, the distance between two bubbles has an obvious impact on the secondary Bjerknes force.