Superconvergence of a nonconforming low order finite element Original Research Article

We investigate a nonconforming finite element on tensor product grids applied to diffusion–convection–reaction equations with dominating convection. This (incomplete nonconforming P2P2) element can be considered as an enriched parametric View the MathML sourceQ1rot element (Rannacher–Turek element). In difference to this View the MathML sourceQ1rot element, one obtains a supercloseness property and superconvergence in the H1H1 seminorm. Additionally, in the case of small diffusion parameters, the enrichment of the View the MathML sourceQ1rot element leads to a stabilization in streamline direction similar to SDFEM.