水下爆炸冲击波数值模拟中的参数影响

为提高数值模拟水下爆炸冲击波的精度，研究了状态方程、网格密度、人工粘性对数值模拟的影响．以球形药包为例，采用有限元程序MSC．Dytran进行数值模拟，将结果与经验公式对比，分析了各参数的影响作用．结果表明，状态方程的形式对结果影响不大，而网格密度有很大影响．为确定最佳的网格密度，定义了一个描述网格密度的无因次量，并给出了不同药量时最佳无因次网格密度的范围．人工粘性能够较好地抑制冲击波压力计算中出现的数值振荡，但同时也引起了冲击波峰值的衰减．调整水的状态方程的系数，能够在保证数值模拟效果的同时，减少水域中的单元数量。

Effect of parameters in numerical simulation of underwater shock wave

In order to improve the numerical simulation of an underwater blast wave, some parameters which have effect on the simulation, such as equation of state(EOS), element density and artificial viscosity, were analyzed. As an example, the underwater shock wave generated by exploding a sphere charge was simulated using the FEM program MSC.Dytran. Comparing the results of numerical simulation with those of experiential formula, the significances of these parameters were known. It was found that the shape of EOS had little effect on the simulation, but the element density had significant effects. Trying to get the optimal element density, a variable without units was defined to describe the density of element, and the optimal scope of this variable was ensured. The artificial viscosity can control the oscillations trailing the shock front, but it also weakened the peak pressure. Adjustment of parameters in EOS was also carried out to reduce the number of elements and get preferable simulation.