基于OpenFOAM的磁流体求解器的开发和应用  

Development and application of OpenFOAM based magnetohydrodynamic solver

作　　者：李尚卿 王伟民 李玉同[1,2,4] Li Shang-Qing;Wang Wei-Min;Li Yu-Tong(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Department of Physics,Renmin University of China,Beijing 100872,China;Songshan Lake Materials Laboratory,Dongguan 523808,China)

机构地区：[1]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190 [2]中国科学院大学物理学院,北京100049 [3]中国人民大学物理学系,北京100872 [4]松山湖材料实验室,东莞523808

出　　处：《物理学报》2022年第11期418-427,共10页Acta Physica Sinica

基　　金：中国科学院先导科技专项(批准号:XDA25010300,XDA25050300);国家自然科学基金(批准号:11827807,11775302)资助的课题.

摘　　要：基于计算流体力学平台OpenFOAM,本文开发了一套可压缩磁流体求解器,并将其应用于二维和三维的跨音速束流模拟.该求解器对OpenFOAM自带的密度基中心差分黎曼求解器rhoCentralFoam进行了修改,植入一个隐式压力分离算法用以控制磁场散度误差并保证模拟结果的数值精度.本文对此求解器进行了检测,证明了它的收敛阶在1—2之间,并将其应用到强激光等离子体的磁流体模拟.利用该求解器,本文讨论了外加均匀轴向磁场对激光等离子体喷流的影响,发现了喷嘴和结节位置与热压比开方之间的线性关系.本文还分析了电容线圈中产生的非均匀磁场对激光等离子体喷流的影响.初步模拟结果表明,当线圈中心磁场相同时,小尺寸线圈产生的磁场会加快喷嘴和结节的形成,等效的均匀轴向磁场更大.此模拟结果可以作为我们将来的磁化喷流实验的参考.同时,这样物理结果表明该磁流体求解器适合做面向激光等离子体实验的工程计算,可以应对构型比较复杂的场合.We develop a compressible magnetohydrodynamic solver to simulate the transonic flows based on an open-source computational fluid dynamics platform OpenFOAM.The solver is achieved by modifying the density-based Riemann solver rhoCentralFoam which adopts a central scheme and is available in OpenFOAM.To improve simulation accuracy and avoid non-physical oscillations,a specialized pressure-implicit algorithm with the splitting of operators is implemented to guarantee the incompressibility of magnetic field.The solver is benchmarked and the convergence rate is between the first and the second order.After benchmark,we apply this solver to magnetohydrodynamic simulations of intense-laser-produced plasma.The influences of uniform axial magnetic field and nonuniform coil-current-induced magnetic field on laser-produced plasma jets are investigated.With the uniform axial magnetic field,the positions of nozzle and the distance between knots are linearly related to square root of thermal over magnetic pressure.With the nonuniform magnetic field generated in the coil,knots are nonlinearly distributed in space and the nozzle position is modulated according to preliminary simulations.In the two kinds of magnetic fields,when the B-field strength is the same at coil center,the magnetic field of relatively small coils can shorten the times of forming nozzles and knots,suggesting that the coil magnetic field is equivalent to a higher uniform one.The simulations can be used as a reference for our future experiment on magnetized laser-produced plasma jet.Meanwhile,our simulation investigation shows that this magnetohydrodynamic solver is suitable for engineering calculation for laser plasma experiments and can deal with the situation with relatively complex configurations.

关 键 词：可压缩磁流体力学求解器 计算流体力学 OpenFOAM程序 强激光等离子体 磁流体模拟 

分 类 号：O35[理学—流体力学]