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arXiv · 2603.08887

On $p$-robust convergence and optimality of adaptive FEM driven by equilibrated-flux estimators

Théophile Chaumont-Frelet·Zhaonan Dong·Gregor Gantner·Martin Vohralík
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Abstract

Building on existing $hp$-adaptive algorithms driven by equilibrated-flux estimators from [ESAIM Math. Model. Numer. Anal. 57 (2023), 329--366] and the references therein, we propose a novel $h$-adaptive algorithm for a fixed polynomial degree $p$. We consider a conforming finite element discretization of the Poisson equation in two or three space dimensions. Supposing piecewise polynomial right-hand side of degree $p-1$, we show that the algorithm yields error contraction at each step, with a contraction factor that is independent of $p$ provided that a certain {\sl a posteriori} verifiable criterion is satisfied. We further show that this algorithm converges at optimal algebraic rate $s$ if the D\"orfler marking parameter is chosen below some specified $p$-independent upper threshold. The constants involved here are $p$-robust, although they may depend on the rate $s$. The theoretical results are supported by numerical experiments, in which the {\sl a posteriori} criterion is always satisfied for one or a few local mesh refinement steps by newest-vertex bisection.

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Théophile Chaumont-Frelet, Zhaonan Dong, Gregor Gantner, Martin Vohralík. 2026-03-09. On $p$-robust convergence and optimality of adaptive FEM driven by equilibrated-flux estimators. https://arxiv.org/abs/2603.08887

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