Deformation and coalescence of ferrodroplets in Rosensweig model using the phase field and modified level set approaches under uniform magnetic fields
Deformation and coalescence of ferrodroplets in Rosensweig model using the phase field and modified level set approaches under uniform magnetic fields
复制标题
DOI：
10.1016/j.cnsns.2020.105213
复制
发表时间：
2020-06
期刊：
影响因子：
--
通讯作者：
Feng Bai;Daozhi Han;Xiaoming He;Xiaofeng Yang
中科院分区：
文献类型：
--
作者：
Feng Bai;Daozhi Han;Xiaoming He;Xiaofeng Yang
采用相场方法和改进的水平集方法，建立了两种多相流数值模型，并对两种模型进行了比较，研究了均匀磁场作用下非磁性粘性介质中铁滴的变形和合并过程.两个数值模型的空间离散化采用有限元法。数值结果表明，在简单的轴对称设置与解析解非常一致。系统地研究了不同磁键数和磁化率对铁液滴形变的影响。利用相场方法和改进的水平集方法研究了均匀磁场下两个小铁滴合并成单个大铁滴的过程。此外，在数值试验中还观察到了两个铁液滴之间的吸引现象。通过与解析解的比较，我们的研究表明，扩散界面（相场）的方法比修改后的水平集方法时，有大的拓扑变形的铁滴表现得更好。其他几个重要的方面，包括流场的演变，磁能分布，界面附近的寄生流，以及在这两种方法中的质量守恒，进行了研究。
By using both a phase field approach and a modified level set approach, two multiphase numerical models are proposed and compared in this paper to investigate the ferrodroplet deformation and merging process in a non-magnetic viscous medium under the influence of uniform magnetic fields. The finite element method is utilized for the spatial discretization of both numerical models. The numerical results show excellent agreement with the analytical solutions in the simple axisymmetric setting. The effects of different magnetic bond numbers and magnetic susceptibility on the deformation of ferrodroplets are systematically investigated. The coalescence process, in which two small ferrodroplets merge into a single larger droplet under uniform magnetic fields, is also studied by using both the phase field approach and the modified level set approach. Moreover the attraction phenomenon between two ferrodroplets, which was previously discovered in numerical experiments, is observed in our numerical tests. By comparing with analytical solutions, our study demonstrates that the diffuse interface (phase field) approach performs better than the modified level set approach when there is large topological deformation of the ferrodroplet. Several other important aspects, including the evolution of the flow field, the magnetic energy distribution, the spurious flows near the interfaces, and conservation of mass in both approaches, are studied as well.