TY - GEN
T1 - Improvements of the CMFD acceleration capability of OpenMOC
AU - Wu, Wenbin
AU - Giudicelli, Guillaume
AU - Smith, Kord
AU - Forget, Benoit
AU - Yao, Dong
AU - Luo, Qi
N1 - Publisher Copyright:
© 2019 American Nuclear Society. All rights reserved.
PY - 2019
Y1 - 2019
N2 - Due to its computational efficiency and geometrical flexibility, the Method of Characteristics (MOC) has been widely used for light water reactor lattice physics analysis. Usually acceleration methods are necessary for MOC to achieve acceptable convergence on practical reactor physics problems. Among them, Coarse Mesh Finite Difference (CMFD) is very popular and can drastically reduce the number of transport iterations. In OpenMOC, CMFD acceleration was implemented but had the limitation of supporting only a uniform CMFD mesh, which would often lead to splitting MOC source regions, thus creating an unnecessary increase in computation and memory use. In this study, CMFD acceleration with a nonuniform Cartesian mesh is implemented into OpenMOC. We also propose a quadratic fit based CMFD prolongation method in the axial direction to further improve the acceleration when multiple MOC source regions are contained in one CMFD coarse cell. Numerical results are presented to demonstrate the improvement of the CMFD acceleration capability in OpenMOC in terms of both efficiency and stability.
AB - Due to its computational efficiency and geometrical flexibility, the Method of Characteristics (MOC) has been widely used for light water reactor lattice physics analysis. Usually acceleration methods are necessary for MOC to achieve acceptable convergence on practical reactor physics problems. Among them, Coarse Mesh Finite Difference (CMFD) is very popular and can drastically reduce the number of transport iterations. In OpenMOC, CMFD acceleration was implemented but had the limitation of supporting only a uniform CMFD mesh, which would often lead to splitting MOC source regions, thus creating an unnecessary increase in computation and memory use. In this study, CMFD acceleration with a nonuniform Cartesian mesh is implemented into OpenMOC. We also propose a quadratic fit based CMFD prolongation method in the axial direction to further improve the acceleration when multiple MOC source regions are contained in one CMFD coarse cell. Numerical results are presented to demonstrate the improvement of the CMFD acceleration capability in OpenMOC in terms of both efficiency and stability.
KW - Coarse mesh finite difference
KW - Method of characteristics
KW - Non-uniform coarse mesh
KW - OpenMOC
KW - Quadratic fit prolongation
UR - https://www.scopus.com/pages/publications/85075389304
M3 - Conference contribution
AN - SCOPUS:85075389304
T3 - International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M and C 2019
SP - 1990
EP - 2001
BT - International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M and C 2019
PB - American Nuclear Society
T2 - 2019 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M and C 2019
Y2 - 25 August 2019 through 29 August 2019
ER -