Characteristics of the pressure wave between compressible vapor bubble and air bubble in an infinite domain

Aeration is a widely adopted and effective approach for mitigating cavitation erosion in hydraulic engineering. The erosion-mitigating effect of aeration depends on the interaction between cavitation bubbles and air bubbles, particularly on the microscopic dynamics of shock wave emission during the collapse of cavitation bubbles, which plays a vital role in determining the severity of cavitation. This study investigates the interaction between cavitation and air bubbles using a three-phase 74compressible phase-change model. The results show that shock wave effects depend critically on the relative sizes and separation distances of the bubbles. The dimensionless Kelvin impulse (anisotropy parameter ζ) is introduced to analyze the relationship between bubble impulse, shock wave energy, and emission timing/location. As ζ increases from 0 to 0.3, the proportion of energy released by the cavitation bubble initially decreases and then increases, reaching a minimum at approximately ζ ≈ 0.15, where the energy contribution is around 75%. When 0 < ζ < 0.15, the position of the shock wave release exhibits a linear relationship with ζ. Further analysis demonstrates the following: Small air bubbles generate an attractive force on cavitation bubbles, steering the micro-jet toward the air bubble. When the air bubble size is 1–2 times that of the vapor bubble, a power-law relationship emerges between ζ and the interaction strength parameter γ. During the initial oscillation cycle of the vapor bubble, the air bubble generally possesses a positive ζ, indicating repulsion from the vapor bubble, whereas the vapor bubble exhibits a negative ζ, indicating attraction toward the air bubble.