Micro-jet dynamics during shock wave interaction with wall-proximal bubbles: Effects of an incident impinging vs glancing shock wave

Abstract

Shock wave–bubble interaction (SBI) in the liquid medium is a fundamental multiphase flow problem that attracts the interest of researchers, yet the effects of propagation direction of the incident shock wave on wall-proximal bubble collapse and micro-jet dynamics remain to be thoroughly investigated. In this Letter, we performed a comprehensive numerical investigation of SBI with different shock wave patterns and pressure amplitudes (ps), including an incident impinging shock wave (ISW) and a glancing shock wave (GSW). Several unique features are observed. For SBI with an incident ISW, the collapse-induced directed jet transits to a regular jet as ps increases, while for an incident GSW, only a regular jet forms. The maximum jet velocity ujetmax for the SBI with an incident ISW is higher than that with an incident GSW under the same ps, which is implied by the Kelvin impulse analysis with IK,ISWtotal=−Vb(∂J0/∂z)ez+IK,wall and IK,GSWtotal=IK,wall+O(ε). In addition, both the minimum equivalent radius and width of the bubble decrease monotonically with increasing ps for the SBI. Compared to SBI with an incident GSW, the incident ISW compresses the bubble to a smaller size, due to the synergistic effect of the wall constraints and the wall-normal pressure gradient induced by the ISW. Finally, the prolongation factor k also decreases monotonically with increasing ps, following a scaling law k∼(1+0.89γ)(ps/p0)−a.