Convective dynamos with intermediate and strong fields
Convective dynamos with intermediate and strong fields
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DOI：
10.1080/03091928208209029
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发表时间：
1982-12
影响因子：
1.3
通讯作者：
Y. Fautrelle;S. Childress
中科院分区：
文献类型：
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作者：
Y. Fautrelle;S. Childress
本文考虑了Soward处理过的弱场Benard型发电机在较高感生磁场水平下的情况。在中间场区域M∼T1/12中发现了两个不稳定源，其中M和T分别是哈特曼数和泰勒数。在磁场扩散的时间尺度上，由于磁场对对流的失稳，解可能在有限时间内爆炸。在更快的时间尺度上，还可能发生与MAC波不稳定相关的动态不稳定。由此得出结论，这种发电机的渐近结构对磁场能量的有效增加是不稳定的。为了模拟发电机在强场下的稳定性，我们考虑了两种近似。首先，对三维平面波中的截断展开进行了数值研究。第二种方法利用一组特殊的常微分方程组，它包含了对流发电机在所有场能量下的许多特征。这两款车型..。
Abstract The weak-field Benard-type dynamo treated by Soward is considered here at higher levels of the induced magnetic field. Two sources of instability are found to occur in the intermediate field regime M ∼ T 1/12, where M and T are the Hartmann and Taylor numbers. On the time scale of magnetic diffusion, solutions may blow up in finite time owing to destabilization of the convection by the magnetic field. On a faster time scale a dynamic instability related to MAC-wave instability can also occur. It is therefore concluded that the asymptotic structure of this dynamo is unstable to virtual increases in the magnetic field energy. In an attempt to model stabilization of the dynamo in a strong-field regime we consider two approximations. In the first, a truncated expansion in three-dimensional plane waves is studied numerically. A second approach utilizes an ad hoc set of ordinary differential equations which contains many of the features of convection dynamos at all field energies. Both of these models ...