标题： 吸积盘中的湍流及其参数化 显示英文标题

标题： Turbulence and its parameterization in accretion discs

摘要： 在剪切盒近似框架下研究了吸积盘湍流。湍流要么由磁旋转不稳定性驱动，要么在非磁性情况下由动量方程中的显式人工强迫项驱动。与磁场情况不同，在磁场情况下大部分耗散发生在盘冕中，在强制的流体力学情况下，大部分耗散发生在盘面附近。在流体力学情况下，提出了椭圆轨道随机激发的证据。当垂直和径向椭圆轨道频率不同时（模拟绕转动黑洞周围的性质），在这两种频率之间的拍频在某些情况下会在时间功率谱中出现峰值。最后，确定了完整的湍流电阻张量，发现如果湍流是由强迫项驱动的，其非对角线成分的符号使得这种效应不能通过剪切-电流效应产生发电机作用。 显示英文摘要

摘要： Accretion disc turbulence is investigated in the framework of the shearing box approximation. The turbulence is either driven by the magneto-rotational instability or, in the non-magnetic case, by an explicit and artificial forcing term in the momentum equation. Unlike the magnetic case, where most of the dissipation occurs in the disc corona, in the forced hydrodynamic case most of the dissipation occurs near the midplane. In the hydrodynamic case evidence is presented for the stochastic excitation of epicycles. When the vertical and radial epicyclic frequencies are different (modeling the properties around rotating black holes), the beat frequency between these two frequencies appear to show up as a peak in the temporal power spectrum in some cases. Finally, the full turbulent resistivity tensor is determined and it is found that, if the turbulence is driven by a forcing term, the signs of its off-diagonal components are such that this effect would not be capable of dynamo action by the shear--current effect.