Meridional circulation in turbulent protoplanetary disks
Meridional circulation in turbulent protoplanetary disks
复制标题
湍流原行星盘中的经向环流
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
F. Masset
中科院分区：
文献类型：
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作者：
S. Fromang;W. Lyra;F. Masset
语境。基于粘性盘理论，最近的一些研究表明原行星盘中存在大规模的经向环流。这种流动可以解释在距太阳较远的地方存在结晶硅酸盐，包括富含钙和铝的夹杂物（CAI）。目标。本文旨在研究湍流原行星盘中是否存在如此大规模的流动。方法。使用湍流原行星盘的高分辨率全局流体动力学和磁流体动力学（MHD）数值模拟来推断此类盘中的流动特性。结果。通过使用显式粘度进行流体动力学模拟，我们证明我们的数值设置不会受到任何数值伪影的影响。上述经向循环在粘性盘和层流盘中很容易恢复并很快建立。在 MHD 模拟中，磁旋转不稳定性会驱动磁盘中的湍流。对长时间尺度上的湍流波动进行平均，结果未能显示任何大规模的经向环流。对模拟的详细分析表明，缺乏经向环流是由于湍流应力张量具有与粘性应力张量不同的垂直剖面。提供了一个简单的模型，成功地解释了磁盘主体中的流动结构。除了这些结果之外，模拟还表明了与标准垂直平均 α 盘模型可能存在的偏差，这应该是未来工作的重点。结论。全电离和湍流原行星盘的全球 MHD 数值模拟与大规模子午流的存在并不一致。因此，正如基于粘性盘理论的最新模型所表明的那样，该过程无法解释距中心恒星较远距离处结晶硅酸盐的存在。
Context. Based on the viscous disk theory, a number of recent studies have suggested there is large-scale meridional circulation in protoplanetary disks. Such a flow could account for the presence of crystalline silicates, including calcium- and aluminum-rich inclusions (CAIs), at large distances from the sun. Aims. This paper aims at examining whether such large-scale flows exist in turbulent protoplanetary disks. Methods. High-resolution global hydrodynamical and magnetohydrodynamical (MHD) numerical simulations of turbulent protoplanetary disks were used to infer the properties of the flow in such disks. Results. By performing hydrodynamic simulations using explicit viscosity, we demonstrate that our numerical setup does not suffer from any numerical artifact. The aforementioned meridional circulation is easily recovered in viscous and laminar disks and is quickly established. In MHD simulations, the magnetorotational instability drives turbulence in the disks. Averaging out the turbulent fluctuations on a long timescale, the results fail to show any large-scale meridional circulation. A detailed analysis of the simulations show that this lack of meridional circulation is due to the turbulent stress tensor having a vertical profile different from the viscous stress tensor. A simple model is provided that successfully accounts for the structure of the flow in the bulk of the disk. In addition to those results, possible deviations from standard vertically averaged α disk models are suggested by the simulations and should be the focus of future work. Conclusions. Global MHD numerical simulations of fully ionized and turbulent protoplanetary disks are not consistent with the existence of a large-scale meridional flow. As a consequence, the presence of crystalline silicates at large distance of the central star cannot be accounted for by that process as suggested by recent models based on viscous disk theory.