Magnetic convection

高温超导材料的发明开创了超导磁体在普通实验室中的应用，并报道了在强磁场中的许多新现象。甚至那些物质如空气、水等也被注意到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，并期望将这种现象应用于各种工业操作。首先，研究了在四极磁铁产生的尖形磁场作用下，正方形封闭空间内空气的热传导。利用尖形磁场驱动稳定空气层的温度分层，并用烟雾可视化，并进行了数值分析。第二个主题是空气在垂直管中的自然通风，该垂直管从上半侧壁加热， 关于我们 放置在中间高度的线圈。在Ra^*=1000和γ=0（无磁场）时，最大上升速度为36，但在γ=1000时增加到90。这估计了磁场对自然通风的增强。我们还测量了超导磁体内腔的内壁温度。在27℃的环境温度下，最低温度达到-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。对带有超导磁体内腔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，使细节变得清晰。在提出了在鼻子周围放置小磁铁来促进人体换气的建议后，我们对管道内的空气流动进行了数值计算。向内流动被发现是加速，但流出被抑制。进一步研究了水作为抗磁性材料的Rayleigh-Benard自然对流。计算的传热速率被发现同意与经典Silveston的数据绘制时，与Braithwaite等人提出的磁瑞利数。总之，磁对流澄清各种系统的定量。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