%0 Journal Article %T Coarse Mesh Rebalance Acceleration Applied to an Iterative Domain Decomposition Method on Unstructured Mesh %+ CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)) %A Odry, N. %A Lautard, J.-J. %A Vidal, J.-F. %A Rimpault, G. %< avec comité de lecture %@ 0029-5639 %J Nuclear Science and Engineering %I Academic Press %V 187 %N 3 %P 240-253 %8 2017-07-31 %D 2017 %R 10.1080/00295639.2017.1320891 %K Coarse mesh rebalance %K domain decomposition method %Z Physics [physics]/Nuclear Theory [nucl-th] %Z Physics [physics]/Nuclear Experiment [nucl-ex]Journal articles %X An iterative domain decomposition method (DDM) is implemented inside the APOLLO3 Sntransport core solver MINARET. Based on a block-Jacobi algorithm, the method inherently suffers a convergencepenalty in terms of both computing time and number of iterations. An acceleration method has to bedeveloped in order to overcome this difficulty. This paper investigates a nonlinear coarse mesh rebalance (CMR)method that favors the way information propagates through the core when domain decomposition is used. Thefundamental idea involves updating each subdomain boundary condition thanks to a core-sized low-ordercalculation on a coarse spatial mesh. The numerical convergence is sped up. Performances are meeting theexpectations since the CMR acceleration systematically succeeds in overbalancing the domain decompositionadditional cost. The aim of such a DDM + CMR algorithm is eventually to introduce more parallelism whensolving the spatial transport equation. Nevertheless, parallel computing is not addressed in this paper. %G English %L cea-02864635 %U https://cea.hal.science/cea-02864635 %~ CEA %~ DEN