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).
维普
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