On the torsion function with mixed boundary conditions

Michiel van den Berg; Tom Carroll

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arXiv · 1911.02336

On the torsion function with mixed boundary conditions

Michiel van den Berg·Tom Carroll

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Abstract

Let $D$ be a non-empty open subset of $\R^m,\,m\ge 2$, with boundary $\partial D$, with finite Lebesgue measure $|D|$, and which satisfies a parabolic Harnack principle. Let $K$ be a compact, non-polar subset of $D$. We obtain the leading asymptotic behaviour as $\varepsilon\downarrow 0$ of the $L^{\infty}$ norm of the torsion function with a Neumann boundary condition on $\partial D$, and a Dirichlet boundary condition on $\partial (\varepsilon K)$, in terms of the first eigenvalue of the Laplacian with corresponding boundary conditions. These estimates quantify those of Burdzy, Chen and Marshall who showed that $D\setminus K$ is a non-trap domain.

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Michiel van den Berg, Tom Carroll. 2020-06-14. On the torsion function with mixed boundary conditions. https://arxiv.org/abs/1911.02336

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