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Pré-Publication, Document De Travail Année : 2009

Discrete Carleman estimates for elliptic operators and uniform controllability of semi-discretized parabolic equations

Résumé

We derive a semi-discrete two-dimensional elliptic global Carleman estimate, in which the usual large parameter is connected to the one-dimensional discretization step-size. The discretizations we address are some families of quasi-uniform meshes. As a consequence of the Carleman estimate, we derive a partial spectral inequality of the form of that proved by G.~Lebeau and L.~Robbiano, in the case of a discrete elliptic operator in one dimension. Here, this inequality concerns the lower part of the discrete spectrum. The range of eigenvalues/eigenfunctions we treat is however quasi-optimal and represents a constant portion of the discrete spectrum. For the associated parabolic problem, we then obtain a uniform null controllability result for this lower part of the spectrum. Moreover, with the control function that we construct, the $L^2$ norm of the final state converges to zero super-algebraically as the step-size of the discretization goes to zero. An observability-like estimate is then deduced.
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Dates et versions

hal-00366496 , version 1 (08-03-2009)
hal-00366496 , version 2 (04-11-2009)

Identifiants

  • HAL Id : hal-00366496 , version 1

Citer

Franck Boyer, Florence Hubert, Jérôme Le Rousseau. Discrete Carleman estimates for elliptic operators and uniform controllability of semi-discretized parabolic equations. 2009. ⟨hal-00366496v1⟩

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