纵向磁场抑制Richtmyer-Meshkov不稳定性机理  

Mechanism of longitudinal magnetic field suppressed Richtmyer-Meshkov instability

作　　者：沙莎[1] 张焕好[2] 陈志华[2] 郑纯[2] 吴威涛 石启陈 Sha Sha;Zhang Huan-Hao;Chen Zhi-Hua;Zheng Chun;Wu Wei-Tao;Shi Qi-Chen(Beijing Institute of Electronic System Engineering,Beijing 100854,China;Key Laboratory of Transient Physics,Nanjing University of Science and Technology,Nanjing 210094,China;School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]北京电子工程总体研究所,北京100854 [2]南京理工大学,瞬态物理国家重点实验室,南京210094 [3]南京理工大学机械工程学院,南京210094

出　　处：《物理学报》2020年第18期239-249,共11页Acta Physica Sinica

基　　金：国家自然科学基金青年科学基金(批准号:11702005);国家自然科学基金(批准号:12072162);中央高校基本科研业务费专项资金(批准号:30919011260)资助的课题.

摘　　要：基于理想磁流体动力学方程组,采用CTU(corner transport upwind)+CT(constrained transport)算法,数值研究了磁场控制下R22气柱界面Richtmyer-Meshkov不稳定性的演化过程.结果描述了平面激波冲击气柱界面过程中激波结构和界面不稳定性的发展;无磁场时,流场结构与Haas和Sturtevant(Hass J F,Sturtevant B 1987 J.Fluid Mech.18141)的实验结果相符;施加纵向磁场后,激波结构的演化基本无影响,但明显抑制了气柱界面的不稳定性.进一步研究表明,激波与界面的作用,使磁感线在界面上发生折射,改变流场的磁场梯度,在内外涡量层上形成磁张力.磁张力的形成,对界面流体产生一个与速度剪切相反的力矩,抑制了界面的失稳及主涡的卷起.另外,磁张力沿界面分布的不均匀,改变磁感线在界面上的聚集程度,放大磁能量,最终增强磁场对气柱界面不稳定性的抑制作用.Based on the ideal magneto-hydro-dynamic equations(MHD)and adopting the CTU(Corner Transport Upwind)+CT(Constrained Transport)algorithm,the Richtmyer-Meshkov(RM)instability of the Gaussian distribution R22 gas column generated by the interaction of a planar shock wave with the gas column in the presence of magnetic field is investigated numerically.The numerical results show that the evolution of shock wave structure and interface instability during the interaction between shock wave and gas column are consistent with the experimental results of Haas and Sturtevant(Hass J F,Sturtevant B 1987 J.Fluid Mech.18141)in the absence of a magnetic field.In the presence of a longitudinal magnetic field,the evolution of the shock structures is almost unaffected,while the density interface appears very smooth and interfacial vortex sequences vanish,which is a clear indication of the RMI suppresion.Moreover,as the shock wave impinges on the interface,the magnetic field lines refract on the interface,resulting in the generation of magnetic field gradient in the flow field,which is not consistent with the scenario in the above case.As a result,a stronger magnetic tension is produced on the inner and outer vorticity layer.Simultaneously,the magnetic tension produces a moment on the interface fluid,which is opposite to the rolling direction of the velocity shear.Therefore,the interface instability and the main vortex rolling-up are effectively suppressed.In addition,the non-uniform distribution of magnetic tensions along the interface changes the aggregation degree of the magnetic lines,amplifying the magnetic strength,and finally enhancing the suppression effect of the magnetic field on the interface instability.

关 键 词：RICHTMYER-MESHKOV 不稳定性 磁流体 激波 圆形气柱 

分 类 号：O354.5[理学—流体力学]