超大规模结构网格CFD数值模拟初步研究

A pilot study on CFD numerical simulation of ultra-large-scale structured grid

基于国家数值风洞(NNW)系统的流固耦合模拟软件平台NNW-FSI,系统性地提出了解决超大规模结构网格生成的重构加密方法,以及基于多重网格粗化技术的壁面距离搜索、重叠网格贡献单元搜索和拼接网格拼接单元搜索算法,并基于同构系统的纯MPI方法和MPI+OpenMP混合并行方法,基于异构系统的MPI+OpenACC混合并行方法,开发了超大规模结构网格CFD数值模拟的前置网格生成模块、流场求解模块和后置显示模块。在国产大型同构和异构集群系统上,实现了百亿级超大规模结构网格在百万核上的CFD数值模拟,取得了良好的并行效率。数值结果表明,该方法具有良好的网格收敛性、多核一致性和计算精度,为下一步的工作展开打下了良好基础。

Based on NNW-FSI,a Fluid-Structure Interaction(FSI)simulation software platform for National Numerical Windtunnel(NNW)systems,several key methods for ultra-large-scale CFD parallelization are systematically proposed in this paper,including the grid reconstruction method for generating ultra-large-scale structured grid,the method for searching wall distance based on the multigrid coarsening technology,the algorithm for searching contribution unit in overset grid,and the algorithm for searching cross unit in the patched grid.Meanwhile,the pre-grid generation module,flow field solving module and post-display module for CFD numerical simulation of the ultra-large-scale structured grid are developed based on the supercomputers with different architectures.For the implementation of parallelization,pure MPI and MPI+OpenMP hybrid parallel methods based on homogeneous platforms are used,and MPI+OpenACC hybrid parallel methods based on heterogeneous platforms are used.Using these methods,ultra-large-scale CFD numerical simulation is realized and achieves good parallel efficiency on different domestic supercomputers,and the largest scale has tens of billions of grids running on millions of CPU cores parallelly.The numerical results show that the proposed method achieves good grid convergence,multi-core consistency and high-precision results,which lays a good foundation for the next-step work.