Hydrodynamic stability in accretion disks under the combined influence of shear and density stratification
Hydrodynamic stability in accretion disks under the combined influence of shear and density stratification
复制标题
剪切和密度分层联合影响下吸积盘的水动力稳定性
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
D. Shalybkov
中科院分区：
文献类型：
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作者：
Günther Rüdiger;Rainer Arlt;D. Shalybkov
考虑了吸积盘的流体动力稳定性。特别的问题是，（稳定的）垂直密度分层和（稳定的）径向昼夜旋转的联合作用是否会引起非轴对称扰动模式的新的不稳定性。著名的Solberg-Hoiland判据并不表明存在这种不稳定性。我们在第2节中对熵和角动量的一般分层中的扰动作的局部分析也没有提出这一点。这证实了Solberg-Hoiland准则的结果也为非轴对称模式的理想流体动力学的框架内，但只有在一个短波近似的小M .A的稳定性的必要条件的框架内，我们发现，只有保守的外力被允许影响稳定盘。由于磁力从来不是保守的，线性磁盘不稳定性应该只存在于磁流体力学制度，其中确实包含磁旋转不稳定性作为一个很有前途的候选人。为了克服数值方法中使用的一些近似，可压缩绝热流体动力学方程被集成，施加初始非轴对称速度扰动，m = 1 tom = 200。只有动能衰减的解才能找到，系统总是根据中心物体重力势的压力平衡而处于垂直平衡分层。
The hydrodynamic stability of accretion disks is considered. The particular question is whether the combined action of a (stable) vertical density stratification and a (stable) radial dierential rotation gives rise to a new instability for nonax- isymmetric modes of disturbances. The existence of such an instability is not suggested by the well-known Solberg-Hoiland criterion. It is also not suggested by a local analysis for disturbances in general stratifications of entropy and angular momentum which is presented in our Sect. 2. This confirms the results of the Solberg-Hoiland criterion also for nonaxisymmetric modes within the frame of ideal hydrodynamics but only in the frame of a short-wave approximation for small m .A s anecessary condition for stability we find that only conservative external forces are allowed to influence the stable disk. As magnetic forces are never conservative, linear disk instabilities should only exist in the magnetohydrodynamical regime which indeed contains the magnetorotational instability as a much-promising candidate. To overcome some of the used approximations in a numerical approach, the equations of the compressible adiabatic hydro- dynamics are integrated, imposing initial nonaxisymmetric velocity perturbations with m = 1t om = 200. Only solutions with decaying kinetic energy are found. The system always settles in a vertical equilibrium stratification according to pressure balance with the gravitational potential of the central object.