Collaborative Research: Supernova Simulation With CHIMERA

千兆级计算机的出现带来了对许多科学问题的物理保真度的大幅提高的希望，但是千兆级计算机的架构特性需要相当大的创新才能有效地使用。这个由三部分组成的合作项目解决了CHIMERA的几个最直接的开发需求，这是一个大规模并行的多物理场代码，专门用于模拟核心坍缩超新星。这些恒星爆炸产生了宇宙中的大部分元素；是中微子、引力波和光子的巨大来源，并导致中子星和黑洞的形成。将CHIMERA扩展到千万亿级平台将进行以下工作：1)对流体动力学进行完整的、经过测试的三维空间域分解，包括处理球极坐标中的坐标奇点的策略；2)一个可扩展的引力场三维泊松求解器，包括牛顿和广义相对论；3)灵活的模块化并行I/O系统；4)热核动力学和中微子输运线性系统的多核解；5)研究分区全局地址空间（PGAS）语言，使计算和通信重叠；6)物理模型和算法的改进。本项目培养的学生和博士后将精通计算科学的几乎每一个重要方面，包括数值线性代数、计算流体动力学、辐射输运和刚性系统解，并将获得大型数据集的管理、分析和可视化的实际经验，以及随之而来的千万亿次计算的硬件和软件环境。普遍化的方法将适用于其他领域，天体物理学的流行魅力使其在超级计算的公共宣传中特别有效。该团队希望继续开展关于计算天体物理学的参观、讲座和演讲，每年吸引400多名K-12学生和教师、200多名大学本科生和数百名其他非科学家。

OCI-0749242MesserOCI 0749248BlondinOCI 0749204MarronettiThe advent of petascale computing brings with it the promise of substantial increases in physical fidelity for a host of scientific problems, but the architectural features of petascale machines will require considerable innovation for effective use. This three-part collaborative project addresses several of the most immediate development needs for CHIMERA, a massively parallel multi-physics code designed expressly to simulate core-collapse supernovae. These stellar explosions produce most of the elements in the Universe; are prodigious sources of neutrinos, gravitational waves, and photons, and lead to the formation of neutron stars and black holes. The extension of CHIMERA to petascale platforms will proceed through: 1) a complete, tested, three-dimensional spatial domain decomposition for the hydrodynamics, including a strategy to handle coordinate singularities in spherical polar coordinates; 2) a scalable three-dimensional Poisson solver for the gravitational field, both Newtonian and general relativistic; 3) a flexible, modular system for parallel I/O; 4) multi-core solutions for the linear systems dominating the thermonuclear kinetics and neutrino transport; 5) investigating Partitioned Global Address Space (PGAS) languages to overlap computation and communication; and 6) improvements to the physical models and algorithms.Students and postdocs trained under this project will be well versed in virtually every important aspect of computational science, including numerical linear algebra, computational fluid dynamics, radiation transport, and stiff system solution, and will gain real world experience with the management, analysis, and visualization of large data sets, and the attendant hardware and software environments of petascale computing. The generalized methods will be applicable in other fields, and the popular allure of astrophysics makes it especially effective in public outreach for supercomputing. The team expects to continue with tours, talks, and presentations on computational astrophysics, reaching each year over 400 K-12 students and teachers, more than 200 college undergraduates, and hundreds of other non-scientists.