On the Coupling of Local Discontinuous Galerkin and Conforming Finite Element Methods

The finite element formulation resulting from coupling the local discontinuous Galerkin method with a standard conforming finite element method for elliptic problems is analyzed. The transmission conditions across the interface separating the subdomains where the different formulations are applied are taken into account by a suitable definition of the so-called numerical fluxes. An error analysis leading to optimal a priori error estimates is presented for arbitrary meshes with possible hanging nodes. Numerical experiments validating the theoretical results are reported.