Tree-based solvers for adaptive mesh refinement code FLASH - I: gravity and optical depths
Tree-based solvers for adaptive mesh refinement code FLASH - I: gravity and optical depths
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用于自适应网格细化的基于树的求解器代码 FLASH - I：重力和光学深度
DOI：
10.1093/mnras/sty015
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发表时间：
2017
影响因子：
4.8
通讯作者：
A. Whitworth
中科院分区：
文献类型：
--
作者：
R. Wunsch;S. Walch;F. Dinnbier;A. Whitworth
我们描述了一种用于mpi并行、自适应网格细化代码{\sc FLASH}的OctTree算法，该算法可用于计算气体自重力，以及用于处理环境漫射辐射的角度平均局部光学深度。该算法只与不同的处理器通信树中需要在本地执行树遍历的部分。这种方法的优点是相对较低的内存需求，这对于需要处理来自许多不同方向的信息的光深度计算尤其重要。该特性还支持将在后续论文中描述的通用基于树的辐射传输算法，并提供至少1500核的出色扩展。重力的边界条件可以是孤立的，也可以是周期的，并且它们可以在每个方向上独立地指定，使用新发展的艾瓦尔德方法的推广。采用{\em自适应块更新}技术，通过部分重用前一时间步长的解来加速重力计算。与{\sc Flash}内部多网格重力求解器的比较表明，基于树的方法提供了一个有竞争力的替代方案，特别是对于具有孤立或混合边界条件的问题。我们评估了几种多极接受标准（MAC），并确定了一个相对简单的APE MAC，该MAC以低计算成本提供了高精度。发现光学深度估计与{\sc RADMC-3D}辐射输运代码的估计非常一致，树求解器的求解速度快得多。我们的算法在{\sc FLASH}代码的标准版本4.0和更高版本中可用。
We describe an OctTree algorithm for the MPI-parallel, adaptive mesh-refinement code {\sc FLASH}, which can be used to calculate the gas self-gravity, and also the angle-averaged local optical depth, for treating ambient diffuse radiation. The algorithm communicates to the different processors only those parts of the tree that are needed to perform the tree walk locally. The advantage of this approach is a relatively low memory requirement, important in particular for the optical depth calculation, which needs to process information from many different directions. This feature also enables a general tree-based radiation transport algorithm that will be described in a subsequent paper, and delivers excellent scaling up to at least 1500 cores. Boundary conditions for gravity can be either isolated or periodic, and they can be specified in each direction independently, using a newly developed generalisation of the Ewald method. The gravity calculation can be accelerated with the {\em adaptive block update} technique by partially re-using the solution from the previous time-step. Comparison with the {\sc Flash} internal multi-grid gravity solver shows that tree based methods provide a competitive alternative, particularly for problems with isolated or mixed boundary conditions. We evaluate several multipole acceptance criteria (MACs) and identify a relatively simple APE MAC which provides high accuracy at low computational cost. The optical depth estimates are found to agree very well with those of the {\sc RADMC-3D} radiation transport code, with the tree solver being much faster. Our algorithm is available in the standard release of the {\sc FLASH} code in version 4.0 and later.
FLASH4 的 GPU 加速 Barnes-Hut 树代码
影响因子：
2
作者：
Banerjee
通讯作者：
Banerjee
SEREN - 用于恒星和行星形成模拟的新 SPH 代码
DOI：
10.48550/arxiv.1102.0721
发表时间：
2011
期刊：
--
影响因子：
--
作者：
Hubber D
通讯作者：
Hubber D