AbstractWe develop simulation tools for the non‐stationary incompressible 2D Navier‐‐Stokes equations. The most important components of the finite element code are: the fractional step ϑ‐scheme, which is of second‐order accuracy and strongly A‐stable, for the time discretization; a fixed point defect correction method with adaptive step length control for the non‐linear problems (stationary Navier‐Stokes equations); a modified upwind discretization of higher‐order accuracy for the convective terms. Finally, the resulting nonsymmetric linear subproblems are treated by a special multigrid algorithm which is adapted to the quadrilateral non‐conforming discretely divergence‐free finite elements. For the graphical postprocess we use a fully non‐stationary and interactive particle‐tracing method. With extensive test calculations we show that our method is a candidat