ABSTRACT The present study performs direct numerical simulations of turbulent channel flows using a spectral method in a large computational domain. Because of applying Fourier discretisation in the spectral method, parallelisation of the method may incur heavy communication overhead, thereby resulting in poor scalability. We design and improve the spectral code by exploring parallel techniques, including domain decomposition and data transposition algorithms. We focus particularly on the 2D domain decomposition and data transpose algorithm with the non-blocking collective operations improves parallel performance, thereby enabling latency mitigation by overlapping the computation and communication. Finally, we evaluate the code on the Nurion supercomputer at KISTI supercomputing centre. The transpose algorithm based on the non-blocking collective operations shows the best performance, which enables 3.55 times faster computing on 256 nodes using 16,384 MPI ranks for the L550 case of grid points than the non-optimised 2D decomposition case.

中文翻译：

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湍流通道流伪谱模拟的 MPI 并行实现

摘要 本研究在大型计算域中使用频谱方法对湍流通道流动进行直接数值模拟。由于在频谱方法中应用傅里叶离散化，该方法的并行化可能会导致大量的通信开销，从而导致较差的可扩展性。我们通过探索并行技术来设计和改进频谱代码，包括域分解和数据转置算法。我们特别关注 2D 域分解和数据转置算法，非阻塞集体操作提高了并行性能，从而通过重叠计算和通信来减少延迟。最后，我们在 KISTI 超级计算中心的 Nurion 超级计算机上评估代码。