Magnetic convection

在发明高温超导材料的开创性工作之后，在普通的实验室里就有了超导磁体，并报道了强磁场中的许多新现象。人们已经注意到，即使是空气、水等物质也会受到强磁场的影响。在本研究项目中，尝试了各种方法来澄清由于强磁场引起的流体对流，并可能期望将来将这种现象应用于各种工业操作。首先，利用四极磁铁产生的尖形磁场，研究了从上加热到下冷却的立方体密闭空间内空气的热传导。温度分层稳定空气层是由尖形磁场驱动的，该磁场以烟雾为显示，并进行了数值分析。第二个主题是空气在垂直管道中的自然通风，从上半侧壁加热，在中间高度放置一个线圈。在Ra^*=1000和γ=0（无磁场）时，最大上升速度为36，而在γ=1000时，最大上升速度为90。这估计了磁场对自然通风的增强作用。我们还测量了超导磁体孔空间的内壁温度。环境温度为27℃，最低温度为-16℃。这警告说，可以说，一个制造商宣布的室温下的孔空间是不正确的。并对这一特性进行了数值分析。用数值方法研究了具有超导磁体孔空间的倾斜立方体内空气的自然对流和磁对流，得到了较为清晰的结果。根据在鼻子周围放置一个小磁铁来促进人体通风的建议，我们对管道内的空气流动进行了数值计算。发现向内流动加速，但流出被抑制。进一步研究了水作为抗磁性材料的瑞利-贝纳德自然对流。当与Braithwaite等人提出的磁瑞利数进行对比时，发现计算的传热率与经典的Silveston数据一致。总之，定量地阐明了各种系统的磁对流。少

After a pioneering work to invent super-conducting materials at high temperature, a super conducting magnet becomes available in usual laboratory with which many new phenomena in a strong magnetic field have been reported. Even those materials such as air, water etc. have been noted to be affected by a strong magnetic field. In the present research project, various approaches were tried to clarify the convection of fluid due to a strong magnetic field with possible future expectation to apply such phenomena to various industrial operations. At first, thermal conduction of air in a cubic enclosure heated from above and cooled from below was studied with a cusp-shaped magnetic field caused by four poles magnet. The temperature stratified stable air layer was driven by the cusp-shaped magnetic field which was visualized with smoke and numerical analyses were carried out simultaneously. Second subject is natural ventilation of air in a vertical tube heated from an upper half side wall with … More a coil placed at mid height. At Ra^*=1000 and γ=0(no magnetic field), maximum rising velocity was 36 but it increased to 90 atγ=1000. This estimated the enhancement of natural ventilation by a magnetic field. We also measured the inside wall temperature of a bore space of a super-conducting magnet. The minimum temperature attained at -16℃ in an ambient temperature of 27℃. This warned that, so to speak, a bore space at room temperature announced by a manufactures is not, correct. This characteristics was also numerically analyzed. The natural and magnetic convection of air in a cube inclined with a bore space of a super-conducting magnet was numerically studied and the details becomes clear. Following a proposal to promote human breezing with a small magnet placed around a nose, we carried out numerical computation for the air flow inside a tube. Inward flow was found to be accelerated but outflow was suppressed. Further more we studied Rayleigh-Benard natural convection of water as a diamagnetic material. The computed heat transfer rate was found to agree with classical Silveston's data when plotted versus the magnetic Rayleigh number proposed by Braithwaite et al.In summary, magnetic convection was clarified for various systems quantitatively. Less