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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。
In order to solve the multi-dimensional multi-group neutron diffusion equation quickly and accurately, two new nonlinear iterative methods based on single-block expansion and double-block finite difference are given. Compared with the existing nonlinear iteration based on double-block expansion, Law made a comparison. Solve the in-interface sub-flow by using nodal expansion technique (or finite difference technique) on two (or single) nodal blocks to update the non-linear nodal correction coefficients, and then perform the coarse net calculation again with the updated non-linear correction coefficients. Solve it by the sub-diffusion equation in the above iterative process. The benchmark calculation shows that the double-block (or single-block) expansion nonlinear iteration method is much faster than the Green function fast method, and the calculation accuracy of the two methods is comparable. However, the finite difference nonlinear iteration method can reach Green function fast method is quite level, and the method can flexibly divide the coarse mesh section further and improve the precision.