【摘要】 为了快速准确地求解多维多群中子扩散方程,给出了基于单节块展开和双节块有限差分两种新的非线性迭代法,并与已有的基于双节块展开的非线性迭代法作了比较。在两个(或单个)节块上通过节块展开技术(或有限差分技术)求解界面中子流,进而更新非线性修正系数,再由更新的非线性修正系数重新进行粗网计算。通过上述迭代过程中子扩散方程得以求解。基准计算表明,双节块(或单节块)展开非线性迭代法比Green函数节快法要快得多,两者计算精度相当;而有限差分非线性迭代法在计算精度和速度上可以达到与Green函数节快法相当的水平,并且该方法可以灵活地对粗网节块作进一步的划分,提高计算精度。更多还原

【Abstract】 Two nonlinear iteration methods based on a onenode nodal expansion (NE) and a twonode finite difference method (FD) were developed to accurately and quickly solve the multidimensional, multigroup neutron diffusion equation. The two methods were compared with the nonlinear iteration method based on a twonode nodal expanion. The interface neutron currents were calculated using either the onenode nodal expanion or the twonode finite difference technique and then the nonlinear coefficients at the interface were updated. The coarse mesh finite difference equations were then solved using the updated nonlinear coefficients. Benchmark calculations showed that the nonlinear iteration method based a one or twonode nodal expansion was considerably faster than the nodal Green’s function method with nearly the same accuracy. The nonlinear finite difference method has almost the same speed and accurcy as the Green’s function method and the accuracy of the finite difference method can be conveniently increased by using more subnodes.更多还原