Numerical study of Richtmyer–Meshkov instability in shocked composite curtain under different initial conditions

The Richtmyer–Meshkov (RM) instability evolution in the shocked composite curtain (A|B/C|A curtain) under different initial conditions is first investigated. The effect of amplitude combination, slope of slip interface, and initial Mach number on the development of RM instability in a composite curtain is obtained. Compared to the single curtain (A|B|A curtain) case, it generates two pairs of vortices at the slip interface, and the perturbation amplitude growth is strongly affected by the slip interface for the composite curtain with a slip interface. Moreover, the mixing efficiency of the shocked composite curtain is larger than that of the single curtain. Both qualitative and quantitative results show that the wave structure and interface morphology of the shocked composite curtain are very different from those of the single curtain. For the shocked composite curtain, when the two interfaces are initially in-phase, it promotes the late growth of vorticity and inhibits the growth of the mixing area, which is the opposite when the two interfaces are initially anti-phase. As the absolute value of the slope increases, the amount of vorticity deposited on the slip interface is smaller, thus reducing the growth of vorticity. However, the growth of the mixing area is less dependent on the slope of the slip interface. The initial Mach number not only accelerates the development of the flow field but also has a strong influence on the spatial and temporal scales of the later stages of the RM instability evolution.