Abstract
Coarse Mesh Finite Difference (CMFD) method is a very effective method to accelerate the iterations for neutron transport calculation. But it can degrade and even fail when the optical thickness of the mesh becomes large. Therefore several methods, including partial current-based CMFD (pCMFD) and optimally diffusive CMFD (odCMFD), have been proposed to stabilize the conventional CMFD method. Recently, a category of “higherorder” prolongation CMFD (hpCMFD) methods was proposed to use both the local and neighboring coarse mesh fluxes to update the fine cell flux, which can solve the fine cell scalar flux discontinuity problem between the fine cells at the bounary of the coarse mesh. One of the hpCMFD methods, refered as lpCMFD, was proposed to use a linear prolongation to update the fine cell scalar fluxes. Method of Characteristics (MOC) is a very popular method to solve neutron transport equations. In this paper, lpCMFD is applied on the MOC code MPACT for a variety of fine meshes. A track-based centroids calculation method is introduced to find the centroids coordinates for random shapes of fine cells. And the numerical results of a 2D C5G7 problem are provided to demonstrate the stability and efficiency of lpCMFD method on MOC. It shows that lpCMFD can stabilize the CMFD iterations in MOC method effectively and lpCMFD method performs better than odCMFD on reducing the outer MOC iterations.
Highlights
Coarse Mesh Finite Difference(CMFD) method is a very effective method to accelerate the iterations for neutron transport calculation[1]
The partial current-based CMFD (pCMFD) method is unconditionally stable for monoenergetic infinite homogeneous problems, it may become less efficient than CMFD for problems with intermediate or smaller coarse mesh sizes[7]
The Fourier analysis and numerical results based on a monoenergetic infinite homogeneous medium problem showed that the optimal θ increases with the optical thickness increasing and is always smaller than the value 1/4 predicted by pCMFD
Summary
Coarse Mesh Finite Difference(CMFD) method is a very effective method to accelerate the iterations for neutron transport calculation[1]. A category of CMFD methods , regarded as “higher-order” prolongation methods (hpCMFD) [9], was proposed to use both the local and neighboring coarse mesh fluxes to update the fine cell flux. One of the hpCMFD methods, refered to lpCMFD, was proposed by Wang and Xiao[4] to use a linear prolongation to update the fine cell scalar fluxes, which will be discussed . It showed that lpCMFD is more stable than conventional CMFD methods and is effective for a wide range of optical thicknesses.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
