A high-performance and portable asymptotic preserving radiation hydrodynamics code with the M1 model
A high-performance and portable asymptotic preserving radiation hydrodynamics code with the M1 model
复制标题
M1 模型的高性能、便携式渐进保持辐射流体动力学代码
DOI：
10.1051/0004-6361/202038579
复制
发表时间：
2020
影响因子：
6.5
通讯作者：
E. Audit
中科院分区：
文献类型：
--
作者：
H. Bloch;P. Tremblin;M. Gonz'alez;T. Padioleau;E. Audit
目标。我们提出了一个新的辐射流体力学代码称为ARK-RT，它使用一个两个时刻的模型与M1封闭关系的辐射传输。此代码旨在为exascale架构上的高性能计算做好准备。
方法.采用有限体积法求解双矩模型。该计划的目的是渐近保持，以准确地捕捉光学厚和薄制度。我们还提出了一个很好的平衡的离散化的辐射通量源项，使用户能够捕捉恒定的通量不连续的不透明度的稳态。我们使用Trilinos库进行线性代数，Kokkos包使我们能够在不同的架构（如多核，众核和GP-GPU）中实现高性能计算和可移植性。
结果ARK-RT能够在自由流动和扩散极限下再现标准测试，包括纯辐射测试和辐射流体力学测试。使用时间隐式求解器是有利的，只要由流体动力学给出的时间步长比辐射传递的显式时间步长大50到100倍，这取决于预处理器和架构。然而，还需要做更多的工作，以确保在所有情况下的稳定。利用ARK-RT研究了对流致密核中电离锋的传播。我们表明，电离前是强稳定的扰动，即使不稳定的对流运动。因此，不稳定性的存在应谨慎解释。总的来说，ARK-RT非常适合研究许多涉及对流和辐射传输的天体物理问题，例如大质量恒星前致密核心中H II区域的动力学，未来的应用可能包括行星大气。
Aims. We present a new radiation hydrodynamics code called ARK-RT which uses a two-moment model with the M1 closure relation for radiative transfer. This code was designed to be ready for high-performance computing on exascale architectures.
Methods. The two-moment model is solved using a finite-volume scheme. The scheme is designed to be asymptotic preserving in order to accurately capture both optically thick and thin regimes. We also propose a well-balanced discretization of the radiative flux source term which allows users to capture constant flux steady states with discontinuities in opacity. We use the library Trilinos for linear algebra and the package Kokkos allows us to reach high-performance computing and portability across different architectures, such as multi-core, many-core, and GP-GPU.
Results. ARK-RT is able to reproduce standard tests in both free-streaming and diffusive limits, including purely radiative tests and radiation hydrodynamics ones. Using a time-implicit solver is profitable as soon as the time-step given by the hydrodynamics is between 50 and 100 times larger than the explicit time-step for radiative transfer, depending on the preconditioner and the architecture. Nevertheless, more work is needed to ensure stability in all circumstances. Using ARK-RT, we study the propagation of an ionization front in convective dense cores. We show that the ionization front is strongly stable against perturbations even with destabilizing convective motions. As a result, the presence of instabilities should be interpreted with caution. Overall, ARK-RT is well-suited to studying many astrophysical problems involving convection and radiative transfer such as the dynamics of H II regions in massive pre-stellar dense cores and future applications could include planetary atmospheres.