This article presents a general framework to estimate the pointwise error of linear partial differential equations. The error estimator is based on the variational multiscale theory, in which the error is decomposed in two components according to the nature of the residuals: element interior residuals and interelement jumps. The relationship between the residuals (coarse scales) and the error components (fine scales) is established, yielding to a very simple model. In particular, the pointwise error is modeled as a linear combination of bubble functions and Green's functions. If residual-free bubbles and the classical Green's function are employed, the technology leads to an exact explicit method for the pointwise error. If bubble functions and free-space Green's functions are employed, then a local projection problem must be solved within each element and a global boundary integral equation must be solved on the domain boundary. As a consequence, this gives a model for the so-called fine-scale Green's functions. The numerical error is studied for the standard Galerkin and SUPG methods with application to the heat equation, the reaction-diffusion equation and the convection-diffusion equation. Numerical results show that stabilized methods minimize the propagation of pollution errors, which stay mostly locally.

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This paper presents an exact pointwise error estimator applied to the transport equation. The error estimate, which is represented by a combination of residual-free bubble and Green’s functions, is computed by postprocessing the finite element solution. The fine or unresolved scales are analyzed applying the variational multiscale method. The technology can be applied to linear and high-order elements. Numerical examples are presented in which the satisfactory results corroborate the theoretical foundations.

Summary In this paper, we present residual‐based error estimators applied to the Stokes problem. Implicit and explicit error estimators are developed to predict the error of the numerical solution obtained by a stabilized finite element formulation. Both error estimators arise from the variational multiscale framework, in which the variational form is split into coarse scales (finite element method solution) and fine scales (committed error). This leads to a local problem set on each element in which the error and the residuals are involved. The different ways of linking the error to the residuals produce two error estimators. Local and global error estimates measured in the H1‐seminorm are provided for triangles and quadrilaterals. As an application, using the local error estimates, an adaptive mesh refinement strategy is implemented in order to optimize the computational resources.

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