燃料棒接触问题的新型自适应预处理方法

Novel Adaptive Preconditioner for Contact Problem in Fuel Rod

通过分析接触前后雅可比矩阵的稀疏结构,构造基于接触压力判断准则的新型自适应预处理方法。在接触压力为零时使用完全的雅可比矩阵作为Preconditioned Jacobian-free Newton-Krylov(PJFNK)方法的预处理矩阵,在接触压力非零时使用雅可比矩阵的块对角作为预处理矩阵。数值试验表明:本文的自适应预处理方法能够有效提升模拟效率,求解总时间与Multiphysics Object-Oriented Simulation Environment(MOOSE)中现有方法相比减少了15.2%~33.1%。

The contact problem between the fuel core block and the cladding is a key point in the simulation of nuclear reactor fuel rods,and the inclusion of a contact model increases the difficulty of solving the set of algebraic equations.By analyzing the sparse structure of the Jacobi matrix before and after contact,a novel adaptive preprocessing method based on the contact pressure judgment criterion is constructed.The full Jacobi matrix is used as the preprocessing matrix for the Preconditioned Jacobian-free Newton-Krylov(PJFNK)method when the contact pressure is zero,and the block diagonal of the Jacobi matrix is used as the preprocessing matrix when the contact pressure is non-zero.Numerical experiments show that the adaptive preprocessing method in this paper can effectively improve the simulation efficiency,and the total solution time is reduced by 15.2%~33.1%compared with the existing methods in Multiphysics Object-Oriented Simulation Environment(MOOSE).