AI 中文总结
该研究通过粘性流体动力学模拟，探究不同外边界条件对黑洞周围平流吸积流结构、激波特性、角动量分布及外流产生的影响，指出需结合初始流入气体的定性与定量特性构建吸积模型。
AI 中文摘要
我们对黑洞（BH）周围粘性流体动力学（HD）流形成的各类吸积盘结构进行了模拟。研究发现，吸积盘结构会受初始流入气体物理参数变化的显著影响，这些物理参数可称为外吸积边界处的外边界条件（OBCs），并可在OBC平面上表示，该平面主要分为热模式和冷模式两类流入气体。模拟中观测到平滑流与激波流，二者均遵循对应OBC的半解析解；有趣的是，某些类型的OBCs可在吸积流中产生具有类喷流特征的激波，而其他OBCs则可产生平滑或无激波的吸积流，这类流可能存在也可能不存在外流。平滑流在平流中可呈现最低和最高两种角动量分布，具体取决于对应的OBCs。此外，吸积流的性质可分为稳态或准稳态，同样受OBCs影响。我们还观测到，对应热模式气体的解相比冷模式气体的解，产生外流的倾向更强。因此，这项关于OBCs的定性研究对理解吸积物理至关重要，可用于辅助吸积盘建模，其作用类似于仅改变流入气体质量吸积率的定量研究。综上，我们认为吸积模型应同时基于初始流入气体的定性和定量特性。
英文摘要
We simulated various accretion disc structures with viscous hydrodynamic (HD) flow around a black hole (BH). We found that the structure of the accretion disc is significantly influenced by changes in the physical parameters of the initial inflowing gases. These physical parameters can be called outer boundary conditions (OBCs) at the outer-accretion boundary and represented on an OBC plane, which is primarily divided into hot-mode and cold-mode inflowing gases. We found smooth and shocked flows in the simulation, which follow the semi-analytical solutions with their OBCs. Interestingly, we observed that certain types of OBCs can produce shocks with jet-like features in the accretion flow. However, other OBCs can produce smooth or shock-free accretion flow, which may or may not have outflows. The smooth flows can display both the lowest and highest angular momentum distributions among the advective flows, depending on the OBCs. Additionally, the nature of the accretion flows can be either steady or quasi-steady, also influenced by the OBCs. We also observed that solutions corresponding to hot-mode gases have a greater tendency to generate outflows compared to those with the cold-mode. Therefore, this qualitative study of OBCs is crucial for understanding accretion physics, which can aid in modeling accretion discs, similar to the quantitative studies (which involve only changing mass accretion rates) of the inflowing gases. Thus, we assert that an accretion model should be based on both the qualitative and quantitative aspects of the initial inflowing gases.
Comments17 pages, 6 figures
