Turbulence in Accretion Disks: Vorticity Generation and Angular Momentum Transport via the Global Baroclinic Instability
Turbulence in Accretion Disks: Vorticity Generation and Angular Momentum Transport via the Global Baroclinic Instability
复制标题
DOI：
10.1086/344743
复制
发表时间：
2002-11
期刊：
影响因子：
--
通讯作者：
H. Klahr;Peter Bodenheimer UCOLick Observatory;C. Physics;I. F. A. U. Astrophysik;U. Tuebingen;H Germany
中科院分区：
文献类型：
--
作者：
H. Klahr;Peter Bodenheimer UCOLick Observatory;C. Physics;I. F. A. U. Astrophysik;U. Tuebingen;H Germany
在本文中，我们提出了全球斜压不稳定作为一个源的剧烈动荡导致角动量输运的开普勒吸积盘。我们表明，通过分析的考虑和三维辐射流体动力学模拟，特别是，原行星盘有一个负的径向熵梯度，这使得它们斜压。二维数值模拟表明，斜压气流是不稳定的，并产生湍流。这些研究结果进行了测试的数值效果进行模拟与正压初始条件，这表明强加的湍流迅速衰减。斜压盘中的湍流向外输送角动量，并产生径向向内的物质吸积。势能被释放，多余的动能被耗散。最后，气体的再加热支持径向熵梯度，形成自洽过程。我们在二维和三维模拟中测量了吸积率，其数值范围为α = -10-9到-10-7 M yr-1，粘性参数为α = 10-4到10-2，它们完全吻合，并且与观测结果相当吻合。湍流在圆盘的（R，R）平面内产生压力波、Rossby波和涡流。我们在一个全球模拟中证明，这些漩涡往往形成于很小的背景噪音中，并且是持久的特征，这已经被认为会导致行星的形成。
In this paper we present the global baroclinic instability as a source for vigorous turbulence leading to angular momentum transport in Keplerian accretion disks. We show by analytical considerations and three-dimensional radiation-hydrodynamic simulations that, in particular, protoplanetary disks have a negative radial entropy gradient, which makes them baroclinic. Two-dimensional numerical simulations show that a baroclinic flow is unstable and produces turbulence. These findings are tested for numerical effects by performing a simulation with a barotropic initial condition, which shows that imposed turbulence rapidly decays. The turbulence in baroclinic disks transports angular momentum outward and creates a radially inward-bound accretion of matter. Potential energy is released, and excess kinetic energy is dissipated. Finally, the reheating of the gas supports the radial entropy gradient, forming a self-consistent process. We measure accretion rates in our two-dimensional and three-dimensional simulations of Ṁ = -10-9 to -10-7 M☉ yr-1 and viscosity parameters of α = 10-4 to 10-2, which fit perfectly together and agree reasonably with observations. The turbulence creates pressure waves, Rossby waves, and vortices in the (R, ϕ)-plane of the disk. We demonstrate in a global simulation that these vortices tend to form out of little background noise and to be long-lasting features, which have already been suggested to lead to the formation of planets.