Hybridizable Discontinuous Galerkin p-adaptivity for wave problems

Abstract. A p-adaptive Hybridizable Discontinuous Galerkin (HDG) method is presented for the solution of wave problems. The HDG method allows to drastically reduce the coupled degrees of freedom of the computation seeking for an approximation of the solution that is defined only on the edges of the mesh. The particular choice of the numerical fluxes driven by the hybridization technique allows to obtain an optimally converging solution not only for the primal unknown but also for its derivative. This characteristic allows to perform a post-process of the solution that provides a super-convergent solution. The discontinuous character of the solution provides an optimal framework for a p-adaptive technique. The post-processed solu-tion of the HDG method is used to construct a cheap and reliable error estimator that drives an element by element modification of the approximation degree. The proposed p-adaptive HDG method is compared with high-order CG computation with static condensation of the interior nodes. A challenging problem is considered for the comparison: a non-homogeneous scattering problem in an open domain