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.