The Formation of Galaxies and Large-Scale Structure

大挑战应用小组竞赛为支持多学科科学家和工程师团队提供了一种机制，以实现1993财政年度高性能计算和通信（HPCC）计划的目标。理想的提案不仅提供了在(1)科学或工程的基本问题上取得重大进展的机会，其解决方案可以通过应用高性能计算技术和资源来推进，或者(2)促进这些进展的使能技术，而且还提供了科学和计算活动之间的重要互动，通常涉及数学，计算机或计算科学家；这将对正在研究的特定科学或工程问题领域或学科之外的高性能计算活动产生影响。这个项目汇集了一个由天体物理学家、计算科学家和计算机科学家组成的平衡的、临界质量的团队，以及两个国家科学基金会超级计算中心的技术资源，集中精力研究目前物理科学中最令人兴奋和最基本的问题之一：“宇宙中大规模结构的起源是什么？星系是如何形成的？”有丰富的观测数据，有足够的物理定律知识和数学技术来理解宇宙结构的起源和演化。然而，由于这些系统固有的复杂性和模拟多长度尺度相互作用的困难，很难将理论与观测相结合。然而，我们的大挑战应用小组（GCAG）成员最近在多尺度数值算法方面的发展，以及它们在可扩展并行超级计算机上的有效实现，应该使研究人员能够克服这些限制。GCAG将探索使用：(i)不同的数值算法（基于网格、基于粒子和混合（网格+粒子））来解决膨胀宇宙中控制气体、辐射、暗物质和引力的物理方程；（ii）不同的自适应策略（自适应网格细化，分层树），以实现高效的多尺度求解器，能够解析超过4-6个数量级的感兴趣的长度尺度；（iii）不同的编程模型（数据并行、SPMD、对象并行），以高效和可移植的方式在不同的并行架构（TMC的CM5、Intel PARAGON、Cray T3D、Convex MPP）上表达这些复杂的自适应算法，供研究人员使用；（iv）新的软件技术（例如pc++），以开发编译器、优化设计和性能分析工具，使上述策略能够最有效地实施，以便揭示为预计在本十年晚些时候实现的万亿次浮点运算系统构建可移植、可扩展应用所需的各种计算和计算机科学问题。这个独特的数值实验室将使研究人员能够将大尺度结构起源的理论与观测到的宇宙进行比较，抛弃不正确的模型，并有望确定可行理论的要素。这次HPCC大挑战将是数据和数据密集型的，将现有的硬件和软件系统以及解决方案推向极限。研究人员将与匹兹堡和伊利诺斯州超级计算机中心的工作人员以及计算机供应商合作，为存储、可视化和分析用于此和其他HPCC应用的大量数值数据集制定切实有效的策略。该奖项由高级项目研究局以及NSF天文学和计算机科学项目提供支持。

Ostriker 9318185 The Grand Challenge Application Groups competition provides one mechanism for the support of multidisciplinary teams of scientists and engineers to meet the goals of the High Performance Computing and Communications (HPCC) Initiative in Fiscal Year 1993. The ideal proposal provided not only the opportunity to achieve significant progress on (1) a fundamental problem in science or engineering whose solution could be advanced by applying high performance computing techniques and resources, or (2) enabling technologies which facilitate those advances, but also significant interactions between scientific and computational activities, usually involving mathematical, computer or computational scientist, that would have impact in high performance computational activities beyond the specific scientific or engineering problem area(s) or discipline being studied. This project brings together a balanced, critical mass team of astrophysicists, computational scientists and computer scientists, as well as the technical resources of two NSF supercomputing centers, to mount a focused attack on what is presently one of the most exciting and fundamental problems in the physical sciences: "What is the origin of large-scale structure in the universe and how do galaxies form?" There is abundant observational data sufficient knowledge of the physical laws and mathematical techniques required to understand the origin and evolution of cosmic structure. Yet, it is difficult to confront theory with observation in detail owing to the inherent complexity of these systems and the difficulty of simulating multiple length-scale interactions. However, recent developments in multiscale numerical algorithms by members of our Grand Challenge Application Group (GCAG) and their efficient implementation on scaleable parallel supercomputers should enable the investigators to overcome these limitations. The GCAG will explore the use of: (i) different numerical algorithms (grid-based, particle-based, and hybrid ( grid+particle) to solve the physical equations governing gas, radiation, dark matter and gravity in an expanding universe; (ii) different adaptation strategies (adaptive mesh refinement, hierarchical tree) to achieve efficient, multiscale solvers capable of resolving length scales of interest over 4-6 orders of magnitude; (iii) different programming models (data parallel, SPMD, object parallel) to express these complex, adaptive algorithms in an efficient and portable way on different parallel architectures (TMC's CM5, Intel PARAGON, Cray T3D, Convex MPP) available to the investigators; and (iv) new software technology (e.g. pC++) to develop compilers, optimization designs and performance analysis tools which allow the most efficient implementation of the above strategies in order to expose the various computational and computer science issues required to construct a portable, scaleable application for teraflop systems expected later in this decade. This unique numerical laboratory-will allow the investigators to compare theories of the origin of large-scale structure with the observed universe, to discard incorrect models and hopefully to determine the elements of a viable theory. This HPCC Grand Challenge will be extremely data and UO intensive, pushing current hardware and software systems and solutions to and beyond their limits. The investigators will work with staffs of the Pittsburgh and Illinois supercomputer centers as well as the computer vendors to develop practical and efficient strategies for the storage, visualization and analysis of massive numerical data sets of use to this and other HPCC applications. This award is being supported by the Advanced Projects Research Agency as well as NSF programs in astronomy and computer sciences.