Adaptive refinement in defeaturing problems via an equilibrated flux a posteriori error estimator

Abstract: An adaptive refinement strategy, based on an equilibrated flux a posteriori error estimator, is proposed in the context of defeaturing problems. Defeaturing consists in removing features from complex domains in order to ease the meshing process, and to reduce the computational burden of simulations. It is a common procedure, for example, in computer aided design for simulation based manufacturing. However, depending on the problem at hand, the effect of geometrical simplification on the accuracy of the solution may be detrimental. The proposed adaptive strategy is hence twofold: starting from a defeatured geometry it allows both for standard mesh refinement and geometrical refinement, which consists in choosing, at each step, which features need to be included into the geometry in order to significantly increase the accuracy of the solution. With respect to other estimators that were previously proposed in the context of defeaturing, the use of an equilibrated flux reconstruction allows us to avoid the evaluation of the numerical flux on the boundary of features. This makes the estimator and the adaptive strategy particularly well-suited for finite element discretizations, in which the numerical flux is typically discontinuous across element edges. The inclusion of the features during the adaptive process is tackled by a CutFEM strategy, in order to preserve the non conformity of the mesh to the feature boundary and never remesh the computational domain as the features are added. Hence, the estimator also accounts for the error introduced by weakly imposing the boundary conditions on the boundary of the added features.