SDFEM with non-standard higher-order finite elements for a convection-diffusion problem with characteristic boundary layers

Considering a singularly perturbed problem with exponential and characteristic layers, we show convergence for non-standard higher-order finite elements using the streamline diffusion finite element method (SDFEM). Moreover, for the standard higher-order space Q_pmathcal {Q}_{p} supercloseness of the numerical solution w.r.t. an interpolation of the exact solution in the streamline diffusion norm of order p+1/2 is proved.