反射激波作用下三维凹气柱界面演化的数值研究

激波与气柱相互作用是Richtmyer-Meshkov不稳定性研究的经典案例.单次激波与二维气柱相互作用已得到广泛关注,但是反射激波再次冲击气柱(尤其是三维气柱)的研究较少,相关演化规律和机理尚不清楚.反射激波再次冲击演化中的气柱界面会产生新的斜压涡量,影响涡量的输运和分布,从而影响界面的演化.本文采用自主开发的HOW...

NUMERICAL STUDY ON THE EVOLUTION OF THREE-DIMENSIONAL CONCAVE CYLINDRICAL INTERFACE ACCELERATED BY REFLECTED SHOCK

The interaction of shock wave with cylindrical interface is fundamental in study of the Richtmyer-Meshkov (RM) instability. Although the RM instability of two-dimensional (2D) cylindrical interfaces under a single shock wave has been extensively studied previously, the interaction of reflected shock (short for reshock) with cylindrical interfaces, especially three-dimensional (3D) cylindrical interfaces has not been investigated thoroughly, with relevant development rules and underlying mechanisms unclear. When the shock wave interacts with the evolving interface after reshock, new baroclinic vorticity appears on the interface and this will have a major influence on the evolution of the interface. In this work, the HOWD (high order WENO and double-flux) solver developed in our group is used to numerically study the reshock effect on the evolution of 2D and 3D concave cylindrical N$_{2}$/SF$_{6}$ (inner/outer phases) interfaces with incident planar shock strength of $Ma=1.29$. This work will focus on the evolution of 2D and 3D concave cylindrical interfaces after the reshock under different reflected distances, which is defined as the distance between the end wall and the center of the gas cylinder. Series of data have been extracted both before and after the reshock, including the schlieren and vorticity images of the evolving gas cylinder and the quantitative data of the geometric position of the feature points on the gas cylinder. The geometrical characteristics of the distorted interface and the generation and distribution of baroclinic vorticity in different stages are analyzed. The results indicate that for different reflected distances, the shapes of the evolving interface and the reshock at the interaction instance affect the generation and distribution of the baroclinic vorticity, resulting in distinct evolution characteristics of the RM instability. For the 3D concave cylindrical interface, the baroclinic vorticity distributed in 3D space at different heights can induce complicated 3D structures of the evolving interface.