A Hybrid MPI/OpenMP Parallelization Scheme Based on Nested FDTD for Parametric Decay Instability
A Hybrid MPI/OpenMP Parallelization Scheme Based on Nested FDTD for Parametric Decay Instability
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DOI：
10.3390/atmos13030472
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发表时间：
2022-03
期刊：
影响因子：
2.9
通讯作者：
Linglei He;Jing Chen;J. Lu;Yubo Yan;Jutao Yang;Guang Yuan;Shuji Hao;Qingliang Li
中科院分区：
文献类型：
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作者：
Linglei He;Jing Chen;J. Lu;Yubo Yan;Jutao Yang;Guang Yuan;Shuji Hao;Qingliang Li
毫秒内产生的参数衰减不稳定性（PDI）是电离层加热中的一种重要物理现象。通常，数值模拟被用来研究PDI机制。它们可以直观地研究PDI的产生和发展过程，这在实验研究中是必要的。当通过显式时域有限差分（FDTD）模拟PDI现象时，空间尺度从千米到厘米，并且时间尺度需要满足Courant-Friedrichs-Lewy条件。由于空间分辨率高，离散时间步长限制严格，因此模拟PDI现象是费时且困难的。虽然嵌套网格技术可以提高计算效率，但并行策略的应用是必要的，在这项研究中，我们提出了一个混合的消息传递接口（MPI）/OpenMP并行化方案来解决上述问题。该方案能够实现MPI任务和OpenMP线程的自适应计算和自动分配，具有一定的灵活性和可移植性。在EISCAT背景参数下，模拟了PDI现象。波型转换和强烈的局部湍流的结果与串行程序的结果一致。通过一个新的模拟算例，研究了空腔深度对静电波和负离子密度空腔的影响。通过使用所提出的并行化方案，仿真时间可以从串行程序的70 h减少到3.6 h。
Parametric decay instability (PDI) generated in milliseconds is an important physical phenomenon in ionospheric heating. Usually, numerical simulations are used to study PDI mechanisms. They can intuitively investigate the generation and development process of PDI, which is necessary in experimental studies. When simulating the PDI phenomenon through the explicit finite-difference time-domain (FDTD), the spatial scale spans from kilometers to centimeters, and the time scale needs to meet the Courant–Friedrichs–Lewy condition. Simulating the PDI phenomenon is time-consuming and difficult due to the high spatial resolution and strict restriction on the discrete time step. Although a nested mesh technique can boost the computational efficiency, the application of a parallel strategy is imperative to further improve it. In this study, we present a hybrid Message Passing Interface (MPI)/OpenMP parallelization scheme to solve the above-mentioned problems. This scheme can achieve an adaptive calculation and automatic allocation of MPI tasks and OpenMP threads, proving its flexibility and portability. Under the EISCAT background parameters, the PDI phenomenon was simulated. The results of the wave mode conversion and intense localized turbulence were identical to those of the serial program. Furthermore, a new simulation example and the effect of the cavity depth on electrostatic waves and negative ion density cavity were investigated. By utilizing the proposed parallelization scheme, the simulation time can be reduced from 70 h for the serial program to 3.6 h.