Axial dipolar dynamo action in the Taylor-Green vortex.
Axial dipolar dynamo action in the Taylor-Green vortex.
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泰勒-格林涡旋中的轴向偶极发电机作用。
DOI：
10.1103/physreve.84.066318
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M. Brachet
中科院分区：
文献类型：
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作者：
G. Krstulovic;Gentien Thorner;Julien;S. Fauve;M. Brachet
我们对泰勒-格林涡旋产生的磁场进行了数值研究。我们证明，周期性边界条件可以通过规定速度和磁场的对称性来模拟现实边界条件。这可以深入了解发电机的一些核心问题：速度波动对发电机阈值的可能影响，以及边界条件对阈值和发电机作用产生的磁场几何形状的作用。特别是，我们表明，通过适当选择磁场的对称性，可以获得与最近实验中观察到的类似的轴向偶极发电机。研究了非线性饱和，并给出了一个简单的模型来解释发电机转变的超临界和亚临界性质的磁普朗特数依赖性。
We present a numerical study of the magnetic field generated by the Taylor-Green vortex. We show that periodic boundary conditions can be used to mimic realistic boundary conditions by prescribing the symmetries of the velocity and magnetic fields. This gives insight into some problems of central interest for dynamos: the possible effect of velocity fluctuations on the dynamo threshold, and the role of boundary conditions on the threshold and on the geometry of the magnetic field generated by dynamo action. In particular, we show that an axial dipolar dynamo similar to the one observed in a recent experiment can be obtained with an appropriate choice of the symmetries of the magnetic field. The nonlinear saturation is studied and a simple model explaining the magnetic Prandtl number dependence of the super- and subcritical nature of the dynamo transition is given.