Augmented spaces, two-level methods, and stabilizing subgrids

Starting from the already known relationship between stabilized methods, augmented spaces and residual-free bubbles (RFB), the paper introduces a possible way of mimicking the effect of RFB just by constructing a suitable subgrid and then solving the standard Galerkin equations on the modified grid. Concentrating on the model problem of linear convection-dominated equations, we give sufficient conditions on the subgrid that ensure stability, and error bounds of the same type of standard stabilizing procedures. Copyright (C) 2002 John Wiley Sons, Ltd.