@article{, author = {Apel, Thomas; Nicaise, Serge; Pfefferer, Johannes}, title = {Adapted numerical methods for the numerical solution of the Poisson equation with $L^2$ boundary data in non-convex domains}, editor = {}, booktitle = {}, series = {}, journal = {SIAM Journal on Numerical Analysis}, address = {}, publisher = {}, edition = {}, year = {2017}, isbn = {}, volume = {55}, number = {4}, pages = {1937-1957}, url = {}, doi = {10.1137/16M1062077}, keywords = {}, abstract = {The very weak solution of the Poisson equation with $L^2$ boundary data is defined by the method of transposition. The finite element solution with regularized boundary data converges in the $L^2(mega)$-norm with order $1/2$ in convex domains but has a reduced convergence order in non-convex domains although the solution remains to be contained in $H^{1/2}(mega)$. The reason is a singularity in the dual problem. In this paper we propose and analyze, as a remedy, both a standard finite element method with mesh grading and a dual variant of the singular complement method. The error order 1/2 is retained in both cases also with non-convex domains. Numerical experiments confirm the theoretical results.}, note = {}, institution = {Universität der Bundeswehr München, Fakultät für Bauingenieurwesen und Umweltwissenschaften, BAU 1 - Institut für Mathematik und Computergestützte Simulation, Professur: Apel, Thomas}, }