Drag computation for incompressible flows with a Nitsche’s type stabilization method

Abstract We study the drag error for the Navier–Stokes equations approximated by conforming low-order finite elements. The numerical scheme uses a SUPG stabilization and a new Nitche’s type stabilization on the whole boundary. We introduce a definition of the discrete drag which contains additional terms resulting from the discrete formulat. We prove O ( h 2 ) convergence for the drag error and illustrate the theoretical results by numerical tests. The extension to other finite element methods is also discussed.