Massively Parallel Mesh-less Analysis System for Fluid-Structure Compied Phenomena in Nuclear Power Plants

核电厂各种现象分析的要求是：能够分析反应堆中的复杂现象，准确分析反应堆中的复杂现象，提高预处理的效率和速度，使主要分析过程无冗余，采用大规模并行计算机以减少时间和存储成本。（1）提出了一种不需要有限元网格的适合大规模并行环境的分析策略;（2）利用这种无网格方法，开发了包括自由表面和振荡体在内的大规模三维分析程序;（3）最后，本文以自由网格法（Free Mesh Method，FMM）为基本技术，开发了考虑热-流耦合效应的大规模并行三维结构非线性动态应力分析系统。利用这种方法，我们开发了流固耦合分析系统。具体地说，（1）开发了用于从基于节点的数据并行分析的区域分解模块，（2）开发了用于结构和流体分析的并行迭代线性求解器，（3）开发了用于评估系统的原型系统，（4）在PC集群上验证了所开发系统的效率，（5）在日立SR 2201和SR 8000上验证了所开发系统的有效性;（6）将所开发系统与用户界面功能集成，由于自由网格法对并行处理的高度适用性，规模耦合分析系统，显示了高并行效率的PC集群，和并行计算机。

The requirements for analyzing various kind of phenomena in nuclear power plants are the capability to analyze the complex phenomena in nuclear reactor, the efficiency and speed of pre-processing for analyzing them accurately, to make the main analysis process seemless and using massively parallel computers for reducing time and storage costs.In this study, therefore, we developed the following key technologies ; (1) introducing a new analysis strategy, which does not need finite element meshes and are suitable for massively parallel environment, (2) using such a meshless method, developing the massively parallel large scale 3-dimensional analysis codes, which includes free surface and oscillate solid, (3) finally, developing the non-linear and dynamic stress analysis system for the massively parallel large scale 3-dimensional structures considering the effect of thermal-fluid coupled analysis.In this study, we used Free Mesh Method (FMM) as a basic technology, which was a kind of meshless methods. Using this method, we developed fluid-structure coupled analysis system. Concretely, (1) developing the domain decomposition module for analyzing in parallel from nodal based data, (2) developing parallel iterative linear solver with the preconditioning for structure and fluid analysis, (3) developing prototype system for evaluate the system, (4) verifying the efficiency of developed system on the PC clusters, (5) verifying the efficiency of developed system on Hitachi SR2201 and SR8000, (6) integrating the developed system with user interface functions.Because of the high applicability of Free Mesh Method to the parallel processing, we could develop the 3-dimensional large, scale coupled analysis system, which showed high parallel efficiency on both PC clusters, and parallel computers.