arXiv 2204.017572022-04astro-ph.IMastro-ph.GA

一种新的用于天体物理模拟的残差分布流体动力学求解器

A New Residual Distribution Hydrodynamics Solver for Astrophysical Simulations

Ben Morton, Sadegh Khochfar, Zhenyu Wu

备注：: 21 pages, 20 figures
DOI：: 10.1093/mnras/stac3427

摘要：

许多天体物理系统只有在其重子气体成分的行为被很好地理解时才能精确地建模。偏微分方程（PDE）求解器的残差分布（RD）族产生相应流体方程的近似解。我们提出了一个新的实现的RD方法。该求解器可以有效地计算流体的演化，在时间和空间上都具有高达二阶精度，在2D和3D中跨越非结构化三角剖分。我们实现了一种新的可变时间步进例程，它采用了漂移机制，大大提高了该方法的计算效率。我们对新的实现进行了广泛的测试，证明了其解决复杂流体结构的固有能力，即使在非常低的分辨率下。我们可以用3-5个分辨率元素来解析复杂的结构，这一点已经在Kelvin-Helmholtz和Sedov爆破测试中得到了证明。我们还注意到，我们发现冷云破坏的时间尺度与一个典型的PPE求解器预测的一致，尽管确切的演变显示出微小的差异。该代码包括三种残差计算模式，LDA，N和混合方案，为平稳流（LDA），极端冲击（N），以及两者（混合）的情况下量身定制。我们比较我们的RD求解器的结果，以国家的最先进的求解器中使用的其他天体物理代码，展示了新方法的竞争力，特别是在低分辨率。这在大规模的天体物理模拟中特别有意义，因为重要的结构，如恒星形成的气体云，通常由少量的流体元素来解决。

英文摘要：

Many astrophysical systems can only be accurately modelled when the behaviour of their baryonic gas components is well understood. The residual distribution (RD) family of partial differential equation (PDE) solvers produce approximate solutions to the corresponding fluid equations. We present a new implementation of the RD method. The solver efficiently calculates the evolution of the fluid, with up to second order accuracy in both time and space, across an unstructured triangulation, in both 2D and 3D. We implement a novel variable time stepping routine, which applies a drifting mechanism to greatly improve the computational efficiency of the method. We conduct extensive testing of the new implementation, demonstrating its innate ability to resolve complex fluid structures, even at very low resolution. We can resolve complex structures with as few as 3-5 resolution elements, demonstrated by Kelvin-Helmholtz and Sedov blast tests. We also note that we find cold cloud destruction time scales consistent with those predicted by a typical PPE solver, albeit the exact evolution shows small differences. The code includes three residual calculation modes, the LDA, N and blended schemes, tailored for scenarios from smooth flows (LDA), to extreme shocks (N), and both (blended). We compare our RD solver results to state-of-the-art solvers used in other astrophysical codes, demonstrating the competitiveness of the new approach, particularly at low resolution. This is of particular interest in large scale astrophysical simulations, where important structures, such as star forming gas clouds, are often resolved by small numbers of fluid elements.

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