A domain decomposition method in APOLLO3$^R$ solver, MINARET

Abstract

International audienceThe aim of this paper is to present the last developments made on Domain Decomposition Methodinside the APOLLO3$^R$ core solver, MINARET. The fundamental idea consists in splitting a large boundaryvalue problem into several similar but smaller ones. Since each sub-problem can be solved independently,the Domain Decomposition Method is a natural candidate to introduce more parallel computing intodeterministic schemes. Yet, the real originality of this work does not rest on the well-tried DomainDecomposition Method, but in its implementation inside MINARET. The first validation elements show aperfect equivalence between the reference and the Domain Decomposition schemes, in terms of both$k_{eff}$ and flux mapping. These first results are obtained without any parallelization or acceleration.Nevertheless, the “relatively“ low increase of computation time due to Domain Decomposition is veryencouraging for future performances. So much that one can hope to greatly increase the precisionwithout any major time impact for users. At last, the unstructured space meshing used in MINARET willeventually be improved by adding an optional non conformal map between subdomains. This associationwill make of the new scheme an efficient tool, able to deal with the large variety of geometries offered bynuclear core concepts