流向磁场抑制 Kelvin-Helmholtz不稳定性机理研究  

Mechanism of suppressing Kelvin-Helmholtz instability by flowing magnetic field

作　　者：石启陈 赵志杰 张焕好[1] 陈志华[1] 郑纯 Shi Qi-Chen;Zhao Zhi-Jie;Zhang Huan-Hao;Chen Zhi-Hua;Zheng Chun(National Key Laboratory of Transient Physics,Nanjing University of Science&Technology,Nanjing 210094,China;School of Mechanical Engineering,Nanjing University of Science&Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学,瞬态物理国家重点实验室,南京210094 [2]南京理工大学机械工程学院,南京210094

出　　处：《物理学报》2021年第15期182-192,共11页Acta Physica Sinica

基　　金：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);江苏省研究生科研与实践创新计划项目(批准号:KYCX20_0252)资助的课题.

摘　　要：采用CTU+CT (corner transport upwind+constrained transport)算法对磁流体动力学方程组进行求解,分别对有无磁场控制条件下开尔文-赫姆霍兹(Kelvin-Helmholtz,KH)不稳定性的演化过程进行数值模拟.数值结果分析了磁场(MA=3.33)对混合层流场涡量和压力演化的影响,并与经典流体力学情况进行对比;另外,还从磁压力和磁张力分布情况对磁场抑制KH不稳定性的机理进行分析.结果表明,外加磁场对混合层结构的演变产生很大的影响,其中,磁压力使涡量在界面处沉积,而磁张力能够产生一个与涡旋转方向相反的力矩,从而对大涡结构起到拉伸破坏作用,最终抑制了涡的卷起.此外,当流动发展到一定阶段,在磁压力、磁张力以及压力场的共同作用下,界面在曲率最大位置处会发生分离,最终形成"鱼钩"状涡结构.The evolution of the Kelvin-Helmholtz(KH) instability in the presence of classical hydrodynamics and magneto-hydro-dynamics is investigated numerically by using the magneto-hydro-dynamic(MHD) equations.The MHD equations are solved with the corner transport upwind plus constrained transport algorithm that guarantees the divergence-free constraint in the magnetic field.The numerical results are used to analyze the effects of magnetic field(MA=3.33) on the vorticity and pressure evolution of mixing layer,and also compared with those in the hydrodynamics situation.Moreover,the mechanism of weakening the effect of magnetic field on the KH instability is revealed from the perspectives of the magnetic pressure and the magnetic tension.The results show that the external magnetic field has a great influence on the flow structure of the mixing layer.Specifically,the magnetic pressure has a major effect in the vorticity deposition on the interface,whereas the magnetic tension generates a torque to counter the scrolling of vortex.As a result,the large vortex structure is stretched and destroyed,and finally restrains the vortex rolling-up.In addition,with the development of mixing layer,the interface will separate at the points of maximum curvature under the joint effect of the magnetic pressure,the magnetic tension and the pressure field,and finally form a fishhook-like vortex structure.

关 键 词：KELVIN-HELMHOLTZ 不稳定性 磁压力 磁张力 磁流体 

分 类 号：O361.3[理学—流体力学]