空气自由场中强爆炸冲击波传播二维数值模拟

编写了适用于模拟具有高密度比、高压力比的强激波问题的二维柱对称多介质流体计算程序。利用有限体积方法求解流体的Euler方程组，采用level set方法捕捉爆炸产物与空气的运动界面，并通过求解物质界面两侧Riemann问题的精确解来计算爆炸产物与空气之间的数值通量。研制了三角形网格自适应技术来实现网格的自动加密和粗化，在保证捕捉激波峰值的前提下有效地提高了计算效率。利用计算程序对1 kt TNT当量的空气自由场强爆炸问题进行数值模拟，计算得到的峰值超压、冲击波到达时间等物理参数与点爆炸理论结果基本一致。

Two dimensional simulation for shock wave produced by strong explosion in free air

Aimed to simulate the propagation of blast wave with high density ratio and high pressure ratio produced by strong explosion in the air, a two dimensional numerical program is written in which the problem is treated as a two-medium compressible flow with sharp material interface in Eulerian grids. In this method, the finite volume method is used to solve the Euler equations, level set method is used to capture the moving interface, and the numerical flux across the interface is calculated by exactly solving the Riemann problem. Mesh adaption technique in triangle meshes is adopted to refine or coarsen the meshes which can both capture the peak overpressure and improve the computational efficiency. One kiloton nuclear charge of strong explosion in free air is simulated. The shock wave parameters, including peak overpressure, shock arrival time and so on, are in consistence with the point explosion theory, which show the accuracy and efficiency of the numerical methods.