磁流体中磁场诱发的气泡偶极子对偏转效应  

The deflection effect of air bubble pair caused by magnetic field in ferrofluids

作　　者：刘菁晗 何永清[1] 毕勤成[2] 宋鹏云[1] LIU Jing-han;HE Yong-qing;BI Qin-cheng;SONG Peng-yun(School of Chemical Engineering, Kunming University of Science and Technology, Kunming 650500, China;Sate Key Laboratory of Multiphase Flow in Power Engineering,Xi’an Jiaotong University, Xi’an 710049, China)

机构地区：[1]昆明理工大学化学工程学院,云南昆明650500 [2]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《磁性材料及器件》2017年第1期5-9,32,共6页Journal of Magnetic Materials and Devices

基　　金：国家自然科学基金资助项目(11502102);昆明理工大学引进人才基金资助项目(KKSY201405111)

摘　　要：在以磁流体为介质的气泡上升可视化实验中,首次观察到两两组合而成的气泡对在磁场作用下会发生偏转,最终其中心连线会与磁场方向平行。为解释这一现象,将气泡简化为具有一定等效磁矩的磁偶极子,针对填充磁流体的Hele-Shaw单元中的气泡,求解麦克斯韦方程获得二维等效磁矩计算公式,进而推导出磁场引发气泡之间的相互作用力表达式。相互作用力可分解为径向分量和切向分量,分析后发现切向分量对气泡对运动的影响符合实验中观察到的偏转现象。气泡本身不具有磁性,在磁场作用下也不会被磁化,但是气泡的存在会改变其周围的磁场分布形成"磁穴",从而会诱导出对附近其他气泡的等效磁力。气泡之间的相互作用力根据其相对位置不同而使气泡对之间发生相互吸引或排斥(临界角度为55°或135°),并使气泡对中心连线趋于磁场方向偏转。We firstly observed that two similar bubbles rising in a Hele-Shaw cell filled with ferrofluids will deflect from their original paths,when a transversal magnetic field is imposed.Furthermore,the bubbles will adjust their positions to make the axis of bubble pair oriented along the field direction.In order to explain this phenomenon,we simplified the air bubble as a magnetic dipole with an effective magnetic moment.The two-dimensional Maxwell equations have been solved to obtain the distribution of the magnetic field.Then the expression of the interaction force between the two bubbles in ferrofluids was derived,which can be decomposed into radial and tangential component,and the tangential component is corresponding to the experimental observed deflection phenomenon.Non-magnetic bubbles can not be magnetized under external magnetic fields,but their existence will disturb the distribution of magnetic field like virtual magnetic holes,which can induce the equivalent magnetic body force on the other bubbles.The bubbles attract or repulse each other depending on their different relative positions(the critical angle is55°or135°).As the interaction force increase,the center line of bubble pair will finally parallel to the field direction.

关 键 词：磁流体 磁场 气泡 等效磁偶极子 Hele-Shaw单元 

分 类 号：O361.3[理学—流体力学] TM27[理学—力学]