Solar wind, magnetosphere and ionosphere dynamics by using common parallel simulation codes

近年来，可用于大规模仿真的超级计算机正迅速从矢量并行机向标量并行机转变。日立和富士通甚至在日本也转向了集群式标量并行机的营销，只有NEC在继续开发矢量并行机。为了实现未来越来越成为主流的标量并行机的高效计算，要求改变数组的顺序以提高缓存的命中率，并引入了三维域分解方法和合并系统的通信方法。通过开发满足这些条件的新型三维磁流体力学程序，首次为大规模标量并联机床的有效利用提供了可能。当然，高速硬传递函数是必要的。使用富士通Primepower HPC2500进行的测试计算表明，在矢量并行机上效率高达40%-70%的3D MHD代码，即使在标量并行机上也能超过20%，这是完全可以预期的。结果表明，即使在标量并行的超级计算机上，用MPI(消息传递接口)Fortran编写的许多MHD/Fluid、粒子和混合代码也可以高性能地执行。这些模拟程序开发的成功结果必将促使我们开展大规模的空间模拟，以研究磁层和电离层动力学以及空间物理中的非线性动力学现象。

In recent years, the supercomputer which can be used for large-scale simulation is changing from the vector-parallel machine quickly to the scalar-parallel machine. Hitachi and FUJITSU shift to marketing of a cluster type scalar-parallel machine even in Japan, and only NEC is continuing development of the vector-parallel machine. In order to achieve a high-efficient computation by scalar-parallel machine which will become the mainstream in future more and more, it is required that the order of array is changed in order to raise hit rate of the cache, and that the three-dimensional domain decomposition method and the communication method by the consolidation system are introduced. By development of new three-dimensional MHD (magnetohydrodynamic) code which satisfies such conditions, it can bring for the first time the possibility of the effective utilization of the large scale scalar-parallel machine. Of course, a high-speed hard transfer function is necessary. The 3D MHD code which has high efficiency of 40-70% in the vector-parallel machine can be certainly expectable that it exceeds 20% even in a scalar-parallel machine from the test calculation using this FUJITSU PRIMEPOWER HPC2500. Thus it turned out that many of MHD/Fluid, Particle and Hybrid codes written by MPI (message Passing Interface) Fortran aree executable with high performance even in the scalar-parallel supercomputers. These successful results in development of simulation codes have surely brought us to carry out a large-scale space simulation in order to study the magnetosphere and ionosphere dynamics and nonlinear kinetic phenomena in space physics.