3-D Stellar Hydrodynamics Simulations for Convective-Reactive Nucleosynthesis

对流反应核合成的 3-D 恒星流体动力学模拟

• 批准号: 1713200
• 负责人: Paul Woodward
• 金额: $ 1.89万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1713200&HistoricalAwards=false
• 关键词: Stellar; Hydrodynamics; Simulations; Convective; Reactive

Astronomical observations are now probing the early stages of the universe, in which galaxies developed and merged, and the formation of structure in the universe and its evolution to the present era was set in motion. An important part of this story is the chemical evolution of galaxies. The formation of the elements in stars and their subsequent dispersal are powerful tracers of structure formation and evolution. This project will simulate on Blue Waters processes deep inside stars that play an important role in the heavy elements they generate. These processes are driven by mixing of gases at the boundaries of convection zones, which can bring new fuels into a convection zone, carrying them down into much hotter regions where they burn very rapidly and activate nuclear reaction networks in a special convective-reactive regime. In this regime, reacting nuclei are transported by the turbulent convection flow on about the same timescale as the reactions take place, so that significant departures from spherical symmetry, even in a statistical sense, can result. This project will use the petascale capabilities of Blue Waters to simulate these brief events in 3D.This project we will build on earlier work on Blue Waters to study a process where the O-shell convection zone in a massive star can work its way to the base of the C-shell convection zone above, leading to ingestion of carbon fuel and an ultimate merger of the two burning shells. The project will compute the resulting nucleosynthesis by following the concentrations of a large number of nuclear isotopes and computing their interactions on a 4-D grid of reduced resolution in space and time. A fine grid is required to accurately advance the turbulent convection flow and to compute the amount of fuel entrained in it at the convection zone boundary. The study will follow the most important species on this fine grid, but will represent on the coarser grid the large number of nuclear reactions from which energy release is minor and has minimal back reaction on the flow. This project will generate a large database of results from the 3-D simulations on Blue Waters of convective boundary mixing in stellar interiors. The project intends to organize this database so that the simulation codes can mine it automatically, comparing it to a variety of potentially useful 1-D models of the mixing process. In terms of broader impacts, the project will make this database and tools available to the community on-line in a useful format, so that it will enable research by many others. In addition, the project will work with the NuGrid collaboration to see that the results are incorporated into data sets that are available to the community for chemical evolution simulations of galaxies and structures in the early universe.

现在的天文观测正在探索宇宙的早期阶段，其中星系的发展和合并，以及宇宙结构的形成和演化到当今时代的启动。这个故事的一个重要部分是星系的化学演化。恒星中元素的形成及其随后的扩散是结构形成和演化的有力示踪剂。 该项目将在 Blue Waters 上模拟恒星内部深处的过程，这些过程在恒星产生的重元素中发挥着重要作用。这些过程是由对流区边界处的气体混合驱动的，这可以将新燃料带入对流区，将它们带到更热的区域，在那里它们非常迅速地燃烧，并在特殊的对流反应状态下激活核反应网络。在这种情况下，反应核在与反应发生大致相同的时间尺度上通过湍流对流传输，因此即使在统计意义上，也可能导致球对称性的显着偏离。 该项目将利用 Blue Waters 的千万亿级能力以 3D 方式模拟这些短暂事件。我们将在 Blue Waters 早期工作的基础上研究一个过程，在该过程中，大质量恒星中的 O 壳对流区可以向上方 C 壳层对流区的底部，导致碳燃料的摄入并最终使两个燃烧壳层合并。该项目将通过跟踪大量核同位素的浓度并计算它们在空间和时间分辨率降低的 4 维网格上的相互作用来计算由此产生的核合成。需要一个精细的网格来精确地推进湍流对流并计算对流区边界处夹带的燃料量。 该研究将跟踪该精细网格上最重要的物质，但将在较粗糙的网格上代表大量核反应，这些核反应释放的能量较小，并且对流动的反反应最小。 该项目将生成一个大型数据库，其中包含恒星内部对流边界混合的 Blue Waters 3D 模拟结果。该项目打算组织这个数据库，以便模拟代码可以自动挖掘它，并将其与混合过程的各种潜在有用的一维模型进行比较。 就更广泛的影响而言，该项目将以有用的格式在线向社区提供该数据库和工具，从而使许多其他人能够进行研究。 此外，该项目将与 NuGrid 合作，将结果纳入数据集中，供社区用于早期宇宙中星系和结构的化学演化模拟。

项目成果

Simulating 3-D Stellar Hydrodynamics using PPM and PPB Multifluid Gas Dynamics on CPU and CPU+GPU Nodes

在 CPU 和 CPU GPU 节点上使用 PPM 和 PPB 多流体气体动力学模拟 3-D 恒星流体动力学

• DOI: 10.1088/1742-6596/1225/1/012020
• 发表时间: 2019-06
• 期刊: Journal of physics. Conference series
• 作者: Woodward, Paul R.;Lin, Pei;Mao, Huaqing;Andrassy, Robert;Herwig, Falk
• 通讯作者: Herwig, Falk

Simulating Stellar Hydrodynamics at Extreme Scale

模拟极端规模的恒星流体动力学

• DOI: 10.1109/mcse.2018.05329811
• 发表时间: 2018-09
• 期刊: Computing in Science & Engineering
• 影响因子: 2.1
• 作者: Woodward, Paul R.;Herwig, Falk;Wetherbee, Ted
• 通讯作者: Wetherbee, Ted