Study of Mechanism of MHD dynamo-Toward Understanding of Geodynamo-

MHD发电机机理研究-了解地球发电机-

• 批准号: 07640532
• 负责人: KIDA Shigeo
• 金额: $ 1.47万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640532/
• 关键词: Dynamo; Thermal convection

The mechanism of generation and sustenance of magnetic field driven thermally in a rotating spherical shell was investigated numerically as one of the simplest models of geody-namo. During the period of the project we obtained the following interesting results. [1] It is the first time in the world that the generation of a strong magnetic field and a quasi-periodic oscillation of magnetic dipole are realized on a computer by solving the MHD equations with-out any simplification. [2] The full three-dimensional structure of the thermal convection which creates the magnetic field was clarified by a detailed analysis of closed streamlines and stagnation points. The relation between the spatial structures of the velocity and the magnetic field is currently being investigated in terms of these streamlines as well as by the eigen-value analysis of the velocity-gradient tensor. [3] It was found that there is a complicated but regular time-variation in both the magnetic and the velocity fields which cause the above-mentioned quasi-periodic reversal of the magnetic dipole moment. [4] A kinematic MHD simulation was performed to reveal that there is a strong spatial correlation between the velocity and the magnetic fields.

作为最简单的大地力学模型之一，对旋转球壳中热驱动磁场的产生和维持机制进行了数值研究。在该项目期间，我们获得了以下有趣的结果。 [1] 这是世界上首次在计算机上通过求解MHD方程而无需任何简化就实现了强磁场的产生和磁偶极子的准周期振荡。 [2] 通过对闭合流线和驻点的详细分析，阐明了产生磁场的热对流的完整三维结构。目前正在根据这些流线以及速度梯度张量的特征值分析来研究速度和磁场的空间结构之间的关系。 [3] 研究发现，磁场和速度场都存在复杂但有规律的时变，从而导致上述磁偶极矩的准周期反转。 [4] 运动学 MHD 模拟表明速度和磁场之间存在很强的空间相关性。

项目成果

K.Araki, H.Kitauchi and S.Kida: "Thermally driven dynamo in a rotating sphericl shell-Relation between the flow structure and the magnetic field generation." RIMS Kokyuroku. 970. 54-63 (1996)

K.Araki、H.Kitauchi 和 S.Kida：“旋转球壳中的热驱动发电机 - 流动结构与磁场生成之间的关系”。

木田重雄: "Periodic reversal of magnetic field generated by thermal convection in a rotating spherical shell" Journal of Physical Society of Japan. (1997)

Shigeo Kida：“旋转球壳中热对流产生的磁场的周期性反转”日本物理学会杂志（1997）。

S.Kida, K.Araki and H.Kitauchi: "Periodic reversals of magnetic field generated by thermal convection in a rotating spherical shell." J.Phy.Soc.Japan. (in print). (1997)

S.Kida、K.Araki 和 H.Kitauchi：“旋转球壳中的热对流产生的磁场周期性反转。”

木田重雄: "Periodic reversals of magnetic field generated by thermal convection in a rotating spherical shell" Journal of Physical Society of Japan. (1997)

Shigeo Kida：“旋转球壳中热对流产生的磁场的周期性反转”日本物理学会杂志（1997 年）。