应核科学与技术学院曹良志教授的邀请，美国密歇根大学核工程与辐射科学系的许云林博士来访我校，并针对数值反应堆计算方法研究开展学术讲座。
报告题目：Transient Multi-level Acceleration for Neutron Transport Equation
时 间：2017年1月4日（周三）上午8:30-10:00
地 点：化工楼五楼会议室
报 告 人：许云林博士
联 系 人：刘宙宇（zhouyuliu@xjtu.edu.cn）
讲座摘要：
Three-dimensional, full core transport modeling with pin-resolved detail for reactor dynamic simulation is important for some multiphysics reactor applications. However, it can be computationally intensive due to the difficulty in maintaining accuracy while minimizing the number of time steps. An innovative Predictor-Corrector Quasi-Static Method (PCQM) is introduced which is based on a Transient Multi-Level (TML) methodology. Two levels of couplings are used between 3D-Transport/3D-CMFD and 3D-CMFD/EPKE. In each level, the original flux equation is solved in the coarse predictor step and then is factorized as an amplitude and a shape function in the corrector step, where the predicted solution is adjusted using multiple fine steps. In the first level 3D-Transort/3D-CMFD coupling, the angular and sub-pin flux shape function in the Boltzmann transport equation assume to vary slowly over time and the CMFD cell wise amplitude function is solved using multiple steps by 3D-CMFD transient equation. In the second level, the CMFD scalar flux calculated in the last step is further corrected by a whole core wise amplitude function generated by EPKE solver. The utilization of hierarchical multi-level neutronics transient solvers achieves the goal to balance the numerical accuracy and computational efficiency. In addition, a new iteration scheme with pin-resolve Thermal-hydraulics feedback and theoretical proof for the accuracy of PCQM are also presented. Finally, a stripe assembly case adopted from the SPERT transient tests is used to demonstrate the accuracy and efficiency of the TML method.
报告人简介：
许云林， 2004年获美国普渡大学核工程博士学位，曾任清华大学副教授，主要研究领域为核反应堆数值模拟方法和程序开发、先进反应堆设计和安全分析、大型线性和非线性数值计算方法等方面。在国际学术刊物上发表论文29篇，其中13篇被SCI 和EI收录。目前参与美国能源部“轻水反应堆先进模拟仿真协同创新中心联合体”项目并负责其三维输运时空动力学程序开发。