A posteriori error estimators for the first-order least-squares finite element method

In this paper, we propose a posteriori error estimators for certain quantities of interest for a first-order least-squares finite element method. In particular, we propose an a posteriori error estimator for when one is interested in ‖ σ − σ h ‖ 0 where σ = − A ∇ u . Our a posteriori error estimators are obtained by assigning proper weight (in terms of local mesh size h T ) to the terms of the least-squares functional. An a posteriori error analysis yields reliable and efficient estimates based on residuals. Numerical examples are presented to show the effectivity of our error estimators.