LOCAL ANALYSIS OF THE LOCAL DISCONTINUOUS GALERKIN METHOD WITH THE GENERALIZED ALTERNATING NUMERICAL FLUX FOR TWO-DIMENSIONAL SINGULARLY PERTURBED PROBLEM

In this paper, we analyze the local discontinuous Galerkin method with the generalized alternating numerical flux for two-dimensional singularly perturbed problem with outflow boundary layers. By virtue of the two-dimensional generalized Gauss-Radau projection and energy technique with suitable weight. function, we obtain the double-optimal error estimate, namely, the convergence rate in L-2-norm out of the outflow boundary layer is optimal, and the width of boundary layer is quasi-optimal, when piecewise tensor product polynomial space on quasi-uniform Cartesian meshes are used. Numerical experiments are given to verify the theoretical results.