Three-dimensional shock-sulfur hexafluoride bubble interaction

The evolution of shock-sulfur hexafluoride (SF6) bubble interaction is investigated using a detailed three-dimensional numerical simulation. The influences of the end wall distance on the bubble evolution are analyzed by using the high-resolution simulations. The results show that vorticities mainly emerge at the interfaces of the shock wave and the SF6 bubble, and a downstream jet is formed, owing to the impingement of the high pressure in the vicinity of the downstream pole of the bubble and the induction of nearby vorticities. Besides, the big vortices of the SF6 bubble could interact with the walls in the y-direction to increase the bubble volume. When the end wall distance is shortened, a short and wide downstream jet is formed, owing to the untimely interaction of the reflected shock wave with the distorted SF6 bubble. Also, a new upstream jet emerges behind the impingement of the reflected shock wave, and there is no interaction between the distorted SF6 bubble and the wall in the y-direction until a very late time. From a quantitative point of view, the discrepancy between the bubble volume and effective bubble volume is larger in the case with a long end wall distance, which has enhanced vorticities and strengthened bubble-wall interaction. Moreover, the reflected shock wave has a dominant compression effect on the distorted SF6 bubble evolution for the two cases with different end wall distances, but for the case with a longer end wall distance, the bubble-wall interaction has a more significant influence than the influence of vorticities on the bubble volume increase. The computational results demonstrate the three-dimensional effects of shock-SF6 bubble interactions, which have not been seen in previous two-dimensional simulations.