计算物理 ›› 2018, Vol. 35 ›› Issue (2): 151-160.DOI: 10.19596/j.cnki.1001-246x.7627

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不可压缩流基于块预处理的并行有限元计算

李凌霄   

  1. 中国科学院计算数学与科学工程计算研究所, 北京 100190
  • 收稿日期:2017-01-17 修回日期:2017-05-23 出版日期:2018-03-25 发布日期:2018-03-25
  • 作者简介:李凌霄(1991-),男,博士研究生,从事不可压流体动力学的有限元数值模拟,E-mail:lilingxiao@lsec.cc.ac.cn

Parallel Finite Element Computation of Incompressible Viscous Flows Based on Block Preconditioning Strategy

LI Lingxiao   

  1. Institute of Computational Mathematics and Scientific/Engineering Computing of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2017-01-17 Revised:2017-05-23 Online:2018-03-25 Published:2018-03-25

摘要: 发展了一个模拟非定常不可压缩粘性流的并行有限元求解器,时间离散使用具有二阶精度的隐式中点格式,基于三维非结构四面体网格剖分,使用高阶混合有限元离散速度场(P2)和压力场(P1).全离散格式产生的代数方程组是大型、稀疏、非对称和病态的,基于修正的压力对流扩散预处理(PCD)和精心设计的子问题迭代执行策略,采用预处理的GMRES迭代法来高效求解线性方程组.利用相同的子问题迭代策略,同时给出基于最小二乘交换子(LSC)预处理的并行效率对比.大量数值算例验证了算法的精度、可扩展性和可靠性.三维驱动方腔流模拟结果(Re=3200.0)清晰地显示了方腔流中主涡(PE)、下游二次涡(DSE)、上游二次涡(USE)、侧壁涡(EWV)和TGL涡的存在.

关键词: 不可压缩Navier-Stokes, 块预处理, GMRES迭代, 混合有限元, 并行计算

Abstract: A parallel finite element solver is developed for simulation of the unsteady incompressible viscous flows. Implicit mid-point scheme is used to discretize time variable. Based on unstructured grid, velocity and pressure are discretized by classical P2-P1 Taylor-Hood mixed finite element. Resulting linear algebraic systems are large-scale, sparse, non-symmetric and ill-conditioned. Using a specially designed iterative strategy, it is solved by preconditioned GMRES method with modified pressure-convection-diffusion(PCD) preconditioner. A number of numerical experiments verify scability and validity of the solver. Especially, driven cavity flow simulation in 3D (Re=3200.0) clearly shows existence of primary eddy, downstream secondary eddy, upstream secondary eddy, end-wall vortices and T-G-like vortices. A parallel efficiency comparison with least-squares commutator(LSC) preconditioner is also given.

Key words: incompressible Navier-Stokes, block preconditioning, GMRES iteration, mixed finite element, parallel computation

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