多物理耦合计算中动态输运问题高效蒙特卡罗模拟方法  

Efficient Monte Carlo algorithm of time-dependent particle transport problem in multi-physics coupling calculation

作　　者：上官丹骅[1] 闫威华 魏军侠[1] 高志明[1] 陈艺冰[1] 姬志成[1] Shangguan Dan-Hua;Yan Wei-Hua;Wei Jun-Xia;Gao Zhi-Ming;Chen Yi-Bing;Ji Zhi-Cheng(Institute of Applied Physics and Computational Mathematics,Beijing 100094,China)

机构地区：[1]北京应用物理与计算数学研究所,北京100094

出　　处：《物理学报》2022年第9期10-16,共7页Acta Physica Sinica

基　　金：中国工程物理研究院科学基金(批准号:CX20200028);国家自然科学基金青年科学基金(批准号:11705011)资助的课题。

摘　　要：多物理耦合计算在众多领域都有重要应用.如果其包含粒子输运过程,用蒙特卡罗方法模拟粒子输运常占据大部分的计算时间,因此多物理耦合计算中动态输运问题的高效蒙特卡罗模拟方法意义重大,其不可避免地依赖于大规模并行.基于动态输运问题的特点,本文提出了两种新方法:一是针对输运燃耗耦合计算的新型计数规约算法;二是动态输运计算样本数自适应算法.两种算法都能在保持计算结果基本不变的前提下使计算时间大幅减少,从而提高了效率.Multi-physics coupling calculation has applications in many important research fields.If particle transport process is included in this calculation,Monte Carlo method is often used to simulate this process and usually a large amount of calculation time is needed.So,efficient Monte Carlo algorithm for time-dependent particle transport problem is important for an efficiently coupling calculation,which inevitably relies on large-scale parallel calculation.Based on the characteristic of time-dependent particle transport problem,two methods are proposed in this paper to achieve high-efficiency calculation.One is a tally-reducing algorithm which is used in the coupling of transport simulation and burnup calculation.By reducing the quantity of data which should be reduced necessarily,this method can reduce the calculation time largely.It can be seen that a new coupling mode for these two processes in MPI environment has a larger value when model scale is larger than the sample size.The other method is an adaptive method of setting the sample size of Monte Carlo simulation.The law of large number assures that the Monte Carlo method will obtain an exact solution when the sample scale tends to infinity.But generally,no one knows which sample scale is big enough for obtaining a solution with target precision in advance.So,the common strategy is to set a huge-enough sample scale by experience and conduct the posterior check for all results.Apparently,this way cannot be efficient because the calculation will go on after the precision of solution has reached an object value.Another popular method is to set the sample size to rely on the relative error of some single calculation.The sample size is enlarged without a break until the relative error is less than some presetting value.This method is not suitable either,because Monte Carlo particle transport simulation will gives feedbacks to other process which is composed of many tallies.It is inappropriate to adjust the sample size according to the relative error of any calculati

关 键 词：多物理耦合计算 动态输运 蒙特卡罗方法 

分 类 号：O411[理学—理论物理]