Nonconforming two-level discretization of stream function form of the Navier-Stokes equations

In this report, we analyze a two-level finite element method for the stream function formulation of the stationary Navier-Stokes equations. This report presents the two-level algorithm and error analysis for the case of nonconforming elements, when approximating a nonsingular solution of the stream function formulation of the Navier Stokes equation.