反射激波冲击重气柱的RM不稳定性数值研究

数值研究了二维气柱在入射激波以及反射激波作用下的Richtmyer-Meshkov(RM)不稳定性发展规律, 采用有限体积法结合网格自 适应技术的VAS2D程序, 精确刻画激波和界面的演化. 入射平面激波的马赫数为1.2, 气柱界面内气体为六氟化硫(SF₆), 环境气体为空气, 激波管的尾端为固壁. 通过改变气柱与尾端之间的距离调节反射激波再次作用已经变形的气柱的时间, 获得不同时刻下已经变形的气柱形态、界面尺寸以及环量演化受到反射激波的影响. 结果表明, 反射激波再次作用气柱时, 气柱所处发展阶段不同, 界面演化规律以及环量随时间的变化也不相同, 反射激波与气柱相互作用过程中的涡量产生和分布与无反射情况差异较大, 揭示了不同情况下界面演化的物理机理.

NUMERICAL STUDY ON THE RM INSTABILITY OF A HEAVY-GAS CYLINDER INTERACTED WITH RESHOCK

The evolution of the Richtmyer-Meshkov(RM) instability of a two-dimensional gas cylinder interacted with incident planar shock and reshock is investigated numerically.The procedure VAS2D based on the finite volume method combined with an adaptive mesh refinement is used to effectively capture the wave propagation and interface deformation.The incident planar shock Mach number is 1.2,and the gas cylinder is filled with sulfur hexafluoride(SF6) surrounded by air,and the shock tube end wall is regarded as a solid wall.In the simulations,the distances from the gas cylinder to the end wall are changed to obtain the influence of the reshock on the gas cylinder shape,the interface scale and circulation variation trend of the evolving interface.It is found that the evolution of the reshock inhomogeneity and the variation of the circulation with time are dependent on the development of the distorted gas cylinder when the reshock arrives.The generation and distribution of the vorticity during the interaction of the reshock with the evolving gas cylinder are different from the case without reshock,which indicates the physical mechanism of the interface evolution under different conditions.