多方气体球引力坍缩中激波的形成和传播

The Formation and Propagation of a Shock Formed during the Gravitational Collapse of a Gaseous Polytrope

本文采用计算流体力学中的高分辨率ＰＰＭ格式，数值模拟了多方气体球的引力坍缩、激波形成和传播，物态方程取成Ｐ＝Ｋ（ｓ）ργ，γ为密度的分段函数，通过绝热指数γ的不同取法对三个模型分别进行了计算，并对引力坍缩、反弹激波形成和传播等三个过程以及不同模型之间计算结果上的一些差异做了比较仔细的分析，得到了一些初步结论。

We simulate numerically the gravitational collapse of a gaseous polytrope and the following formation and propagation of a shock,using a high resolution scheme in computational fluid dynamics called PPM(The Piecewise Parabolic Method).The equation of state is simply taken as p=k(s)ργ,here γ is piecewise functions of density ρ.We do Calculations respectively on four models in which the values of γ are different.We make relatively detailed analysis about the three processes of collapsing,shock formation and shock propagation,and about the differences between results of different models.Finally we get some primary conclusions:the outward propagation of compression waves and the infalling material are two factors of the shock formation;the Mach number is less than 1 where the shock forms and once generated the shock propagates outward immediately and goes out of the entire(iron-core)polytrope quickly with its strength decreasing first and increasing later.After the γ becomes larger,the bounce occurs under a lower density, the position where the shock forms moves outward a bit;and it plays a role in delaying the bounce and decreasing the violence degree of the explosion.