准球形、时间相关粘性吸积流：一维结果
Quasi-Spherical, Time-Dependent Viscous Accretion Flow: One-Dimensional Results
摘要：
研究了非旋转黑洞周围一维准球形跨音速吸积流中由于角动量转移而引起的平流吸积流的不稳定性。该代码的设计包括粘性的影响，流体动力学组件保持严格的拉格朗日和重映射方法在没有粘性的角动量，而粘性组件通过隐式方法更新粘性角动量传递。我们进行了两个测试，以证明适合的增长研究的代码。首先，我们模拟了黑洞周围的无粘、低角动量、带激波的跨音速吸积流，然后模拟了牛顿体周围的亚音速、自相似的ADAF解。两种模拟都非常好地拟合了相应的分析曲线。然后，我们模拟了旋转，粘性，跨音速流体与冲击。我们表明，对于低粘度参数，稳定的冲击在更大的距离是可能的。当粘性系数较大时，激波后盘中角动量的传递效率较高，激波结构振荡。此外，当激波漂移到更大的距离时，会产生二次内激波。我们表明，内激波是外激波膨胀的直接结果，也是由于内音速点附近更有效的角动量转移而产生的具有$\partial l / \partial r < 0$的区域。我们发现，所有的磁盘参数，包括发射率，振荡与相同的周期的冲击振荡。我们的模拟可能对低频QPO有影响，例如，GRO J1655-40和XTE J1550-564。
英文摘要：
We investigated the instability of advective accretion flow as a consequence of angular momentum transfer in one-dimensional, quasi-spherical transonic accretion flow around a non-rotating black hole. The code is designed to include the effects of viscosity; the hydrodynamics component preserves angular momentum strictly with Lagrangian and remap method in absence of viscosity, while the viscosity component updates viscous angular momentum transfer through the implicit method. We performed two tests to demonstrate the suitability of the code for accretion study. First, we simulated the inviscid, low angular momentum, transonic accretion flow with shocks around a black hole, and then the subsonic, self-similar ADAF solution around a Newtonian object. Both simulations fitted the corresponding analytical curves extremely well. We then simulated a rotating, viscous, transonic fluid with shocks. We showed that for low viscosity parameter, stable shocks at larger distance are possible. For higher viscosity parameter, more efficient angular momentum transfer in the post-shock disk makes the shock structure oscillatory. Moreover, as the shock drifts to larger distances, a secondary inner shock develops. We showed that the inner shock is the direct consequence of expansion of the outer shock, as well as creation of regions with $\partial l / \partial r < 0$ due to more efficient angular momentum transfer near the inner sonic point. We showed that all disk parameters, including emissivity, oscillate with the same period as that of the shock oscillation. Our simulation may have implication for low frequency QPOs, e.g., GRO J1655-40 and XTE J1550-564.
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