Convection in rotating spherical shells and its dynamo action
Convection in rotating spherical shells and its dynamo action
复制标题
旋转球壳中的对流及其发电机作用
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
Radostin D Simitev
中科院分区：
文献类型：
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作者：
F. Busse;E. Grote;Radostin D Simitev
地球等天体的演化特点是热量从内部传输到外部。通常，通过传导和辐射传递热量的基本静态（或接近静态）状态在内部的全部或部分中是不稳定的，并且会发生对流。与分子传导和辐射不同，对流对物体的旋转状态相当敏感，除非粘度非常高，如类地行星的地幔。科里奥利力对流体运动的作用通常会抑制对流热传输的效率，而振荡运动和湍流可以克服旋转的抑制影响的方式提出了一些最有趣的动力学问题。自然界最常选择的抵消强旋转影响的方法是产生磁场。通过洛伦兹力，新的参与者进入了力的平衡，并且显然促进了更有效的能量传输。在本章中，我们打算首先讨论对流的动力学问题，然后转向通过发电机过程产生的磁场在改变对流流的结构及其传输热量的能力方面可能发挥的作用。第 2 节介绍了基本方程和数值方法。在第 3 节中，我们简要回顾了旋转球形流体壳中对流的发生。第 4 节讨论了随着瑞利数增加而产生的典型分岔场景，并产生具有相干结构的湍流对流。第 5 节讨论了当前可计算的参数范围中的发电机过程。基于超扩散方案的数值解不会被考虑，因为它们往往会引入人为效应（Zhang 和 Jones，1997；Grote 等人，2000a）。第 6 节考虑了在存在主导科里奥利力的情况下磁场和对流之间的相互作用。第 8 节提到了未来研究的未决问题。
The evolution of celestial bodies such as the Earth is characterized by the transport of heat from the interior to outside. Typically the basic static (or nearly static) state in which heat is transported by conduction and radiation is unstable in all or in parts of the interior and convection flows occur. Unlike molecular conduction and radiation, convection flows are rather sensitive to the state of rotation of the body, unless the viscosity is very high as in the mantles of the terrestrial planets. The action of the Coriolis force on fluid motion usually inhibits the efficiency of the convective heat transport, and the ways in which oscillatory motions and turbulence may overcome the inhibiting influence of rotation pose some most interesting dynamical problems. A way chosen most frequently by nature to counteract the effects of strong rotation is the generation of a magnetic field. Through the Lorentz force a new participant enters the balance of forces and evidently facilitates a more efficient transport of energy. In this chapter, we intend to discuss first the dynamical problems of convection and then turn to the roles that magnetic fields generated through the dynamo process may play in changing the structure of convection flows and their capacity for transporting heat. In Section 2 the basic equations and the numerical approach are introduced. In Section 3 we review briefly the onset of convection in rotating spherical fluid shells. The typical bifurcation scenarios that develop as the Rayleigh number increases and give rise to turbulent convection with its coherent structures are discussed in Section 4. In Section 5 the dynamo process in the presently computationally accessible parameter regime is discussed. Numerical solutions based on hyperdiffusivity schemes will not be considered since they tend to introduce artificial effects (Zhang and Jones, 1997; Grote et al., 2000a). The interaction between magnetic fields and convection flows in the presence of a dominant Coriolis force is considered in Section 6. Open problems of future research are mentioned in Section 8.