Petascale Computational Fluid Dynamics

这项拟议的研究将开发一种自适应计算流体动力学求解器，将实现持续的千万亿次性能。成熟的有限元方法将与各向异性自适应网格程序相结合，为解决流体流动问题提供强大的工具，在这些问题中，边界层和剪切层发展出高度各向异性的解，只能通过自适应来定位和解决。这些流动问题可能涉及复杂的几何形状和复杂的物理结构，如流体湍流和多相相互作用，导致离散化如此之大，以至于只有千万亿次模拟才能提供完整解决方案所需的资源。将使用两个应用程序来开发计算方法。这些是尾缘噪声模拟（可压缩-显式），ii)两相环流模拟，iii)心血管模拟（均不可压缩隐含）；每一项研究都对目前人们知之甚少的流体物理学提供了基本的科学见解。知识价值。将开发将自适应CFD求解器扩展到千万亿次性能的算法，以保持对新兴架构（多核、CELL、时钟速率、总线、缓存）和网络（带宽、延迟、通信布局/映射、异步通信）的响应可伸缩性。这个解算器和其他解算器将通过并行、各向异性自适应网格的发展而实现，这大大减少了准确表示各向异性物理所需的元素。这两项开发都将由一个千万亿级仿真器指导，该仿真器不会干扰堆或堆栈内存，适合MPI层，并在出现系统故障时准确预测性能。提出的应用将有助于更好地理解湍流的复杂物理，湍流产生的噪声，多相流以及人体心血管系统中力学和生物学的相互作用。这种基本的科学见解将从高保真度模拟中获得，这将是同类中的第一次，并将通过千兆级资源和算法实现。更广泛的影响。千万亿次自适应CFD求解器将证明，强大的开源软件，适用于非常广泛的流动物理，可以维持千万亿次的性能，为所有基于连续的PDE求解器提供了一条路径，极大地扩展了我们国家的建模和仿真能力。此外，千兆级仿真器将扩展到其他类的并行代码。来自不同子领域的学生将有大量机会共同应对所提出的挑战。拟议的千万亿级应用将影响国家需求的关键领域，包括能源、环境和改善患者护理。

This proposed research will develop an adaptive computational fluid dynamics solver that will achieve sustained petaflop performance. A mature finite element method will be paired with anisotropic adaptive meshing procedures to provide a powerful tool for attacking fluid flow problems where boundary and shear layers develop highly anisotropic solutions that can only be located and resolved through adaptivity. These flow problems can involve complicated geometries and complex physics such as fluid turbulence and multiphase interactions, resulting in discretizations so large that only petascale simulation offers the resources required for a complete solution. Two applications will be used to develop the computational methodology. These are simulation of trailing edge noise (compressible-explicit), ii) two-phase annular flow, and iii) cardiovascular simulation (both incompressible implicit); each yielding fundamental scientific insight into currently, poorly understood flow physics.Intellectual Merit.Algorithms to extend an adaptive CFD solver to petaflop performance will be developed to maintain scaling in the response to emerging architectures (multicore, CELL, clockrate, bus, cache) and networks (bandwidth, latency, communication layout/mapping, asynchronous communication). This solver and others will be enabled by developments in parallel, anisotropic adaptive meshing that affords a dramatic reduction in the elements required to accurately represent anisotropic physics. Both developments will be guided by a petascale emulator that does not perturb the heap or stack memory, fits within an MPI layer and predicts performance accurately in the presence of system faults. The proposed applications will lead to a better understanding of the complex physics of turbulent flow, noise produced by turbulent flows, multiphase flows and the interaction of mechanics and biology in the human cardiovascular system. This fundamental scientific insight will be gained from high fidelity simulations that will be the first of their kind, and will be made possible by petascale resources and algorithms.Broader Impacts.A petascale adaptive CFD solver will demonstrate that robust, open source software, applicable to a very broad range of flow physics, can sustain petaflop performance, providing a path for all continuum-based PDE solvers to follow, greatly extending our nations modeling and simulation capacity. Additionally, the petascale emulator will be extended to other classes of parallel codes. There will be an abundance of opportunities for students from diverse sub-fields to work together on the challenges proposed. The proposed petascale applications will impact critical areas of national need including energy, environment and improved patient care.