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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2011 Volume 397, Pages 115–125 (Mi znsl4670)

This article is cited in 16 papers

On a canonical extension of Korn's first and Poincaré's inequality to $\mathsf H(\operatorname{Curl})$

P. Neff, D. Pauly, K.-J. Witsch

Universität Duisburg-Essen, Fakultät für Mathematik, Essen, Germany

Abstract: We prove a Korn-type inequality in $\overset\circ{\mathsf H}(\operatorname{Curl};\Omega,\mathbb R^{3\times3})$ for tensor fields $P$ mapping $\Omega$ to $\mathbb R^{3\times3}$. More precisely, let $\Omega\subset\mathbb R^3$ be a bounded domain with connected Lipschitz boundary $\partial\Omega$. Then, there exists a constant $c>0$ such that
\begin{equation} c\|P\|_{\mathsf L^2(\Omega,\mathbb R^{3\times3})}\leq\|\operatorname{sym}P\|_{\mathsf L^2(\Omega,\mathbb R^{3\times3})} +\|\operatorname{Curl}P\|_{\mathsf L^2(\Omega,\mathbb R^{3\times3})} \tag{0.1} \end{equation}
holds for all tensor fields $P\in\overset\circ{\mathsf H}(\operatorname{Curl};\Omega,\mathbb R^{3\times3})$, i.e., all
$$ P\in\mathsf H(\operatorname{Curl};\Omega,\mathbb R^{3\times3}) $$
with vanishing tangential trace on $\partial\Omega$. Here, rotation and tangential trace are defined row-wise. For compatible $P$ (i.e., $P=\nabla v$), $\operatorname{Curl}P=0$, where $v\in\mathsf H^1(\Omega,\mathbb R^3)$ a vector field having components $v_n$, for which $\nabla v_n$ are normal at $\partial\Omega$, the estimate $(0.1)$ is reduced to a non-standard variant of the Korn's first inequality:
$$ c\|\nabla v\|_{\mathsf L^2(\Omega,\mathbb R^{3\times3})}\le \|\operatorname{sym}\nabla v\|_{\mathsf L^2(\Omega,\mathbb R^{3\times3})}. $$
For skew-symmetric $P$ ($\operatorname{sym}P=0$) the estimate $(0.1)$ generates a non-standard version of the Poincaré. Therefore, the estimateis a generalization of two classical inequalities of Poincaré and Korn.

Key words and phrases: Korn's inequality, gradient plasticity, theory of Maxwell's equations, Helmholtz' decomposition, Poincaré/Friedrichs type estimate.

UDC: 517

Received: 14.12.2011

Language: English


 English version:
Journal of Mathematical Sciences (New York), 2012, 185:5, 721–727

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