8th European Conference on Numerical Mathematics and Advanced Applications (ENUMATH 2009), Uppsala, Sweden, 29 June - 03 July 2009, pp.875-882
The Galerkin finite element method (FEM) is used for solving the incompressible Navier Stokes equations in 2D. Regular triangular elements are used to discretize the domain and the finite-dimensional spaces employed consist of piece wise continuous linear interpolants enriched with the residual-free bubble (RFB) functions. To find the bubble part of the solution, a two-level FEM with a stabilizing subgrid of a single node is described in our previous paper [Int. J. Numer. Methods Fluids 58, 551-572 (2007)]. The results for backward facing step flow and flow through 2D channel with an obstruction on the lower wall show that the proper choice of the subgrid node is crucial to get stable and accurate solutions consistent with the physical configuration of the problems at a cheap computational cost.