New massively parallel scheme for Incompressible Smoothed Particle Hydrodynamics (ISPH) for highly nonlinear and distorted flow
New massively parallel scheme for Incompressible Smoothed Particle Hydrodynamics (ISPH) for highly nonlinear and distorted flow
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DOI：
10.1016/j.cpc.2018.06.006
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
X. Guo;B. Rogers;S. Lind;P. Stansby
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文献类型：
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作者：
X. Guo;B. Rogers;S. Lind;P. Stansby
本文提出了一种新的大规模并行格式，用不可压缩光滑粒子流体动力学（ISPH）的无网格方法模拟超过1亿个粒子的自由表面流动。作为一种压力投影方法，ISPH需要解决一个稀疏矩阵的压力泊松方程（PPE），这是不平凡的大问题，其中的粒子是不断发展的稀疏移动。新方案使用Hilbert空间填充曲线和单元链表来映射整个域，从而可以很容易地实现域分解和负载平衡，以利用几何局部性来减少内存缓存访问的延迟。计算域可以使用消息传递接口（MPI）细分为12，000多个分区，用于分区之间的通信。负载平衡是使用开源的Zoltan库使用新的粒子加权系统来实现的。为了解决使用数万个分区的大型问题的PPE，使用了开源PETSc库，该库需要HYPRE BoomerAMG预处理器来确保ISPH的快速收敛。代码的性能以英国为基准。国家超级计算机ARCHER。结果表明，区域分解与空间填充曲线可以有效地处理不规则分布的粒子创建一个良好的平衡计划，表明该方法是非常匹配的高度不规则的子域和非均匀分布的ISPH自由表面模拟。基准测试结果表明，大规模并行ISPH代码可以实现超过90%的效率为PPE的解决方案，但计算矩阵系数的效率下降时，使用超过12000个分区，使整体效率超过43%，高达6144 MPI分区，突出未来的改进需要。这项工作表明，Zoltan和PETSc库可以有效地与ISPH结合，以提供开发大规模并行ISPH工具包的能力。
A new massively parallel scheme is developed to simulate free-surface flows with the meshless method incompressible smoothed particle hydrodynamics (ISPH) for simulations involving more than 100 million particles. As a pressure-projection method, ISPH requires the solution of a sparse matrix for the pressure Poisson equation (PPE) which is non trivial for large problems where the particles are moving with continuously evolving sparsity. The new scheme uses a Hilbert space filling curve with a cell-linked list to map the entire domain so that domain decomposition and load balancing can be achieved easily to take advantage of geometric locality in order to reduce latency in memory cache access. The computational domain can be subdivided into more than 12,000 partitions using the message passing interface (MPI) for communication between partitions. Load balancing is achieved using the open-source Zoltan library using a new particle weighting system. To solve the PPE for large problems using tens of thousands of partitions, the open-source PETSc library is used which requires the HYPRE BoomerAMG preconditioner to ensure rapid convergence for ISPH. The performance of the code is benchmarked on the U.K. National Supercomputer ARCHER. The results show that domain decomposition with a space filling curve can efficiently treat irregularly distributed particles creating a well-balanced scheme demonstrating that the approach is well matched to the highly irregular subdomains and non-uniform distribution of ISPH free-surface simulations. The benchmark results show that massively parallel ISPH code can achieve over 90% efficiency for the solution of the PPE, but the efficiency of computing matrix coefficients decreases when using more than 12000 partitions giving overall efficiencies in excess of 43% up to 6144 MPI partitions, highlighting future improvements required. The work demonstrates that the Zoltan and PETSc libraries can be effectively combined with ISPH to offer the capability of developing a massively parallel ISPH toolkit.