MAGNETOROTATIONAL TURBULENCE IN STRATIFIED SHEARING BOXES WITH PERFECT GAS EQUATION OF STATE AND FINITE THERMAL DIFFUSIVITY
MAGNETOROTATIONAL TURBULENCE IN STRATIFIED SHEARING BOXES WITH PERFECT GAS EQUATION OF STATE AND FINITE THERMAL DIFFUSIVITY
复制标题
具有完美气体状态方程和有限热扩散率的分层剪切箱中的磁旋转湍流
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
P. Rossi
中科院分区：
文献类型：
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作者：
G. Bodo;F. Cattaneo;A. Mignone;P. Rossi
本文对平均磁通为零的分层剪切箱中的湍流和发电机作用进行了数值研究。我们假设流体遵循完美气体定律，并且具有有限（恒定）的热扩散系数。计算从一个等温状态开始，该等温状态跨越中平面上下三个尺度高度。经过长时间的瞬态后，各层稳定到一种稳定状态，在这种状态下，边界外的热损失由耗散加热来平衡。我们确定了两种制度。第一种是传导状态，热量主要通过传导传递，密度随高度而降低。在大热扩散率的极限下，这种情形类似于我们所熟悉的等温情形。第二种是对流状态，在较小的热扩散系数值下观察到，在这种状态下，层变得不稳定，无法进行翻转运动，热量主要由平流携带，整个层的密度几乎保持不变。在后一种恒定密度制度下，我们观察到大规模发电机作用的证据，导致传输效率相对于导电情况大幅增加。
We present a numerical study of turbulence and dynamo action in stratified shearing boxes with zero mean magnetic flux. We assume that the fluid obeys the perfect gas law and has finite (constant) thermal diffusivity. The calculations begin from an isothermal state spanning three scale heights above and below the mid-plane. After a long transient the layers settle to a stationary state in which thermal losses out of the boundaries are balanced by dissipative heating. We identify two regimes. The first is a conductive regime in which the heat is transported mostly by conduction and the density decreases with height. In the limit of large thermal diffusivity this regime resembles the more familiar isothermal case. The second is the convective regime, observed at smaller values of the thermal diffusivity, in which the layer becomes unstable to overturning motions, the heat is carried mostly by advection, and the density becomes nearly constant throughout the layer. In this latter constant-density regime we observe evidence for large-scale dynamo action leading to a substantial increase in transport efficiency relative to the conductive case.