The Richtmyer-Meshkov instability occurring on a heavy gas (SF6) bubble surrounded by N2 is numerically investigated in the present work. The interface evolution,shock focusing and jet development are emphasized. Numerical schlieren images and distributions of pressure,density and vorticity are exhibited for an incident shock wave of Mach number 1.23. The jet velocity, circulation and baroclinic torque versus time as well as peak values of pressure and density in the flow field are quantitatively analyzed. The results indicate that SF6 gas bubble accelerated by a planar shock wave has a strong cumulative energy effect so that it produces nearly ideal shock focusing and point source explosion phenomenon near the downstream pole within the bubble interface, which directly results in a secondary wave pattern and a slender jet moving in the streamwise direction. Compared with the secondary wave pattern,the incident shock wave brings on more intense baroclinic torque and vorticity.%数值研究了平面激波冲击氮气环境中SF6气泡界面的Richtmyer-Meshkov不稳定性,重点关注其中的激波聚焦及射流的产生和发展过程.在入射激波马赫数为1.23的情况下,给出了压力、密度、数值纹影和涡量等物理量的演化图像,定量分析了流场中压力最大值、密度最大值、射流速度、环量和斜压力矩随时间的变化关系.计算结果表明,平面激波冲击SF6气泡过程有很强的聚能效应,在气泡内部靠近下游极点处发生激波近似理想聚焦和点爆炸现象,直接导致出现二次波系以及向下游运动的细长射流结构.相比入射激波,二次波系产生斜压力矩和涡量的能力要弱得多.
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