Magnetic convection

在发明了高温超导材料的开创性工作之后，超导磁体在常规实验室中出现了，并报道了许多在强磁场中出现的新现象。甚至那些物质，如空气、水等，也被注意到受到强磁场的影响。在本研究项目中，人们试图用不同的方法来阐明强磁场引起的流体对流现象，并有望在未来将这种现象应用到各种工业操作中。首先，利用四极磁铁产生的尖形磁场，研究了立方体封闭腔内空气的热传导。温度分层稳定空气层由尖形磁场驱动，并用烟幕可视化，同时进行了数值分析。第二个主题是用…从上半侧壁加热的竖直管内空气的自然通风更像是一个放置在中等高度的线圈。当Ra^*=1000时，γ=0(无磁场)时，最大上升速度为36，而当γ=1000时，上升速度增加到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洞空间的内壁温度。在环境温度为27℃时，在-16℃时达到的最低温度。这警告说，可以说，制造商宣布的室温钻孔空间是不正确的。并对这一特性进行了数值分析。对具有超导磁体孔洞空间的倾斜立方体内空气的自然对流和磁对流进行了数值研究，得到了较为详细的结果。根据一项建议，在鼻子周围放置一个小磁铁来促进人类的微风，我们对管子内的空气流动进行了数值计算。向内流动被加速，但流出被抑制。此外，我们还研究了水的Rayleigh-Benard自然对流作为一种抗磁材料。由Braithwaite等人提出的磁瑞利数作图时，计算的换热速率与经典的Silveston数据一致。总之，各种体系的磁对流得到了定量的阐明。较少

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