Methods and Applications of Analysis

Volume 16 (2009)

Number 2

Very Weak Estimates for a Rough Poisson-Dirichlet Problem with Natural Vertical Boundary Conditions

Pages: 157 – 186

DOI: http://dx.doi.org/10.4310/MAA.2009.v16.n2.a2

Author

Vuk Milišić

Abstract

This work is a continuation of [3]; it deals with rough boundaries in the simplified context of a Poisson equation. We impose Dirichlet boundary conditions on the periodic microscopic perturbation of a flat edge on one side and natural homogeneous Neumann boundary conditions are applied on the inlet/outlet of the domain. To prevent oscillations on the Neumann-like boundaries, we introduce a microscopic vertical corrector defined in a rough quarter-plane. In [3] we studied a priori estimates in this setting; here we fully develop very weak estimates à la Nečas [17] in the weighted Sobolev spaces on an unbounded domain. We obtain optimal estimates which improve those derived in [3]. We validate these results numerically, proving first order results for boundary layer approximation including the vertical correctors and a little less for the averaged wall-law introduced in the literature [13, 18].

Keywords

Wall-laws; rough boundary; Laplace equation; multi-scale modelling; boundary layers; error estimates; natural boundary conditions; vertical boundary correctors

2010 Mathematics Subject Classification

35B27, 65Mxx, 76D05, 76Mxx

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