偏心对汇聚激波诱导的RM不稳定性影响的数值研究

发布时间：2018-08-22 09:25

【摘要】：数值研究汇聚激波与四种形状(圆形、小振幅单模、大振幅单模和正方形)的二维气柱界面相互作用,激波汇聚中心与界面同心和不同心(即偏心)时Richtmyer-Meshkov(RM)不稳定性的发展规律,重点考察界面中心的压力及混合区面积在两种情况下随时间的变化.数值方法使用VAS2D程序,该方法采用有限体积法结合网格自适应技术,能够达到时间和空间的二阶精度.结果表明,偏心情况下RM不稳定性是其在同心情况下的扰动和偏心小扰动叠加的结果.在本文采用的偏心程度下(20%),偏心对于圆形无扰动界面发展的影响主要表现在后期界面出现微小扰动结构;而对于单模和正方形这种原本有扰动的界面,偏心使扰动结构呈现不对称及扭曲,同时也影响了界面中心压力和混合区面积,因而加剧了不稳定性的发展.
[Abstract]:The interaction of convergent shock wave with four shapes (circular, small amplitude single mode, large amplitude single mode and square) is numerically studied. The evolution of Richtmyer-Meshkov (RM) instability is studied when the shock convergence center is concentric with the interface and the center is different (i.e. eccentricity). The pressure of the interface center and the area of the mixed zone are investigated with time. The numerical method uses VAS2D program. The finite volume method combined with mesh adaptive technique can achieve the second order accuracy of time and space. The results show that the RM instability under eccentricity is the result of the superposition of the disturbance in concentric case and the small disturbance in eccentricity. Under the eccentricity of this paper (20%), the influence of eccentricity on the development of circular unperturbed interface is mainly reflected in the appearance of micro-disturbance structure at the later stage, but in the case of single mode and square interface, which is originally perturbed. Eccentricity causes asymmetry and distortion of the disturbed structure, and also affects the central pressure of the interface and the area of the mixed zone, thus exacerbating the development of instability.
【作者单位】：中国科学技术大学近代力学系先进推进实验室;
【基金】：国家自然科学基金(11302219;11272308)资助项目
【分类号】：O354.5

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