Magnetohydrodynamic convection in accretion discs
Magnetohydrodynamic convection in accretion discs
复制标题
吸积盘中的磁流体动力对流
DOI：
10.1093/mnras/stab974
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发表时间：
2021
影响因子：
4.8
通讯作者：
Held L
中科院分区：
文献类型：
--
作者：
Held L
对流已经在吸积盘领域讨论了几十年，既作为角动量传输的手段，也因为它通过热传输控制盘的垂直结构的作用。如果气体被充分电离并被弱磁场穿过，对流可能会以非平凡的方式与磁旋转不稳定性（MRI）相互作用。最近，MRI的垂直分层局部模拟报告了角动量输运的相当大的变化，如通过应力与热压比α测量的，当认为存在对流时。虽然MRI湍流可以作为对流的热源，但尚不清楚这两种不稳定性如何动态地相互作用。在这里，我们调查他们的相互作用，在受控的数值实验和隔离的通用功能，他们的相互作用。我们进行垂直分层，3D磁流体动力学剪切盒模拟与保守的，有限体积codepluto一个完美的气体状态方程。我们发现两种不稳定性之间的相互作用的两个特征性结果：（a）直MRI和（B）MRI/对流循环，后者表现出对流为主和MRI为主的流动的交替阶段。在后一阶段，我们发现α增加了近一个数量级，达到峰值0.08。此外，我们发现，在非线性阶段的对流采取大尺度和振荡的对流单体的形式。对流也可以帮助MRI持续降低Rm。最后，我们讨论了我们的结果如何帮助解释模拟矮新星。
Convection has been discussed in the field of accretion discs for several decades, both as a means of angular momentum transport and also because of its role in controlling discs’ vertical structure via heat transport. If the gas is sufficiently ionized and threaded by a weak magnetic field, convection might interact in non-trivial ways with the magnetorotational instability (MRI). Recently, vertically stratified local simulations of the MRI have reported considerable variation in the angular momentum transport, as measured by the stress to thermal pressure ratio α, when convection is thought to be present. Although MRI turbulence can act as a heat source for convection, it is not clear how the two instabilities will interact dynamically. Here, we investigate their interplay in controlled numerical experiments and isolate the generic features of their interactions. We perform vertically stratified, 3D magnetohydrodynamic shearing box simulations with a perfect gas equation of state with the conservative, finite-volume codepluto. We find two characteristic outcomes of the interaction between the two instabilities: (a) straight MRI and (b) MRI/convective cycles, with the latter exhibiting alternating phases of convection-dominated and MRI-dominated flow. During the latter phase, we find that α is enhanced by nearly an order of magnitude, reaching peak values of ∼0.08. In addition, we find that convection in the non-linear phase takes the form of large-scale and oscillatory convective cells. Convection can also help the MRI persist to lower Rm than it would otherwise do. Finally, we discuss how our results help interpret simulations of dwarf novae.
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DOI：
10.1086/589915
发表时间：
2008
期刊：
The Astrophysical Journal
影响因子：
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作者：
M. Pessah;Chi
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DOI：
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发表时间：
1980
期刊：
影响因子：
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作者：
R. Tayler
通讯作者：
R. Tayler
DOI：
--
发表时间：
2006
期刊：
Proceedings of the International Astronomical Union
影响因子：
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作者：
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DOI：
10.1086/173269
发表时间：
1993
期刊：
The Astrophysical Journal
影响因子：
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作者：
D. Lin;J. Papaloizou;W. Kley
通讯作者：
W. Kley