Inner Boundary Condition in Quasi-Lagrangian Simulations of Accretion Disks
Inner Boundary Condition in Quasi-Lagrangian Simulations of Accretion Disks
复制标题
吸积盘准拉格朗日模拟中的内边界条件
DOI：
10.3847/2041-8213/ab800e
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Y. Lithwick
中科院分区：
文献类型：
--
作者：
A. Dempsey;D. Muñoz;Y. Lithwick
在粘性演化吸积盘的模拟中，内边界条件尤为重要。如果处理不当，它会很快导致不正确的行为，因为粘性时间在内边界附近最短。最近的工作已经确定了正确的内边界欧拉模拟。但在准拉格朗日模拟中（例如，SPH、移动网格和无网格），其中通过在有限区域内去除质量来模拟内边界，内部密度分布通常变得异常耗尽。在这里，我们展示了如何在这样的代码中应用边界条件，通过一个简单的修改通常的方法：当一个删除的质量，一个必须加快剩余的材料，使磁盘的角动量不变。我们表明，与1D和2D移动网格（AREPO）模拟，该计划的工作所需的粘性不断变化的磁盘。它不产生虚假的密度耗尽，是独立的质量去除率，只要磁盘是充分解决和质量去除率是不是太极端，触发不稳定性。这种“无扭矩”的质量去除技术允许使用准拉格朗日代码来模拟粘性演化盘，同时包括各种额外的效果。作为一个例子，我们应用我们的计划的吸积盘扰动的一个非常大的行星，其中磁盘演化到粘性稳态的二维模拟。
In simulations of viscously evolving accretion disks, the inner boundary condition is particularly important. If treated incorrectly, it induces incorrect behavior very quickly, because the viscous time is shortest near the inner boundary. Recent work has determined the correct inner boundary in Eulerian simulations. But in quasi-Lagrangian simulations (e.g., SPH, moving mesh, and meshless), where the inner boundary is modeled by removing mass within a finite zone, the inner density profile typically becomes anomalously depleted. Here we show how the boundary condition should be applied in such codes, via a simple modification of the usual approach: when one removes mass, one must speed up the remaining material so that the disk’s angular momentum is unchanged. We show with both 1D and 2D moving-mesh (AREPO) simulations that this scheme works as desired in viscously evolving disks. It produces no spurious density depletions and is independent of the mass removal rate, provided that the disk is adequately resolved and that the mass removal rate is not so extreme as to trigger instabilities. This “torque-free” mass removal technique permits the use of quasi-Lagrangian codes to simulate viscously evolving disks, while including a variety of additional effects. As an example, we apply our scheme to a 2D simulation of an accretion disk perturbed by a very massive planet, in which the disk is evolved to viscous steady state.
圆盘：吸积和扭矩作为质量比和圆盘粘度的函数
DOI：
10.3847/1538-4357/abab95
发表时间：
2020
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Duffell, Paul C.;D’Orazio, Daniel;Derdzinski, Andrea;Haiman, Zoltan;MacFadyen, Andrew;Rosen, Anna L.;Zrake, Jonathan
通讯作者：
Zrake, Jonathan
影响因子：
4.8
作者：
Yi-Lei Tang;A. MacFadyen;Z. Haiman
通讯作者：
Yi-Lei Tang;A. MacFadyen;Z. Haiman