LARGE-SCALE AZIMUTHAL STRUCTURES OF TURBULENCE IN ACCRETION DISKS: DYNAMO TRIGGERED VARIABILITY OF ACCRETION
LARGE-SCALE AZIMUTHAL STRUCTURES OF TURBULENCE IN ACCRETION DISKS: DYNAMO TRIGGERED VARIABILITY OF ACCRETION
复制标题
吸积盘中湍流的大尺度方位角结构：发电机触发的吸积变化
DOI：
10.1088/0004-637x/744/2/144
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
T. Henning
中科院分区：
文献类型：
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作者：
M. Flock;N. Dzyurkevich;H. Klahr;N. J. Turner;N. J. Turner;T. Henning
我们调查的意义，大规模的方位角，磁性和速度模式的磁旋转不稳定性（MRI）的吸积盘湍流。我们进行三维全球分层原行星盘模型的全球理想MHD模拟。我们的域跨越π/4、π/2、π和2 π的方位角。与完整的2 π模型相比，我们观察到限制方位域模型π/2和π/4的高达100%的更强磁场和更强湍流。我们表明，对于这些模型的麦克斯韦应力较大，由于强轴对称磁场产生的α Ω发电机。大的径向扩展的轴对称环向场触发吸积应力的时间放大。所有模型在北方半球（上盘）显示正发电机-α。宇称在每个模型中是不同的，并且在40个局部轨道的时间尺度上变化。在2 π模型中，环向场相对于中平面大多是反对称的。MRI湍流的涡流是高度各向异性的。湍流速度和磁场的主要波长在一到两个磁盘尺度高度之间。在中面，磁倾角从8 °-9 °增加到12 °-13 °。我们的结论是，方位角范围的π是足够的再现大多数湍流性质的三维全球分层模拟磁化吸积盘。
We investigate the significance of large-scale azimuthal, magnetic, and velocity modes for the magnetorotational instability (MRI) turbulence in accretion disks. We perform three-dimensional global ideal MHD simulations of global stratified protoplanetary disk models. Our domains span azimuthal angles of π/4, π/2, π, and 2π. We observe up to 100% stronger magnetic fields and stronger turbulence for the restricted azimuthal domain models π/2 and π/4 compared to the full 2π model. We show that for those models the Maxwell stress is larger due to strong axisymmetric magnetic fields generated by the αΩ dynamo. Large radial extended axisymmetric toroidal fields trigger temporal magnification of accretion stress. All models display a positive dynamo-α in the northern hemisphere (upper disk). The parity is distinct in each model and changes on timescales of 40 local orbits. In model 2π, the toroidal field is mostly antisymmetric with respect to the midplane. The eddies of the MRI turbulence are highly anisotropic. The major wavelengths of the turbulent velocity and magnetic fields are between one and two disk scale heights. At the midplane, we find magnetic tilt angles around 8°–9° increasing up to 12°–13° in the corona. We conclude that an azimuthal extent of π is sufficient to reproduce most turbulent properties in three-dimensional global stratified simulations of magnetized accretion disks.