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Analysis of a new augmented mixed finite element method for linear elasticity allowing ℝ𝕋 0 - ℙ 1 - ℙ 0 approximations

Gabriel N. Gatica (2006)

ESAIM: Mathematical Modelling and Numerical Analysis

We present a new stabilized mixed finite element method for the linear elasticity problem in ℝ 2 . The approach is based on the introduction of Galerkin least-squares terms arising from the constitutive and equilibrium equations, and from the relation defining the rotation in terms of the displacement. We show that the resulting augmented variational formulation and the associated Galerkin scheme are well posed, and that the latter becomes locking-free and asymptotically locking-free for Dirichlet...

Analysis of a non-standard mixed finite element method with applications to superconvergence

Jan Brandts (2009)

Applications of Mathematics

We show that a non-standard mixed finite element method proposed by Barrios and Gatica in 2007, is a higher order perturbation of the least-squares mixed finite element method. Therefore, it is also superconvergent whenever the least-squares mixed finite element method is superconvergent. Superconvergence of the latter was earlier investigated by Brandts, Chen and Yang between 2004 and 2006. Since the new method leads to a non-symmetric system matrix, its application seems however more expensive...

Analysis of Compatible Discrete Operator schemes for elliptic problems on polyhedral meshes

Jérôme Bonelle, Alexandre Ern (2014)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

Compatible schemes localize degrees of freedom according to the physical nature of the underlying fields and operate a clear distinction between topological laws and closure relations. For elliptic problems, the cornerstone in the scheme design is the discrete Hodge operator linking gradients to fluxes by means of a dual mesh, while a structure-preserving discretization is employed for the gradient and divergence operators. The discrete Hodge operator is sparse, symmetric positive definite and is...

Analysis of patch substructuring methods

Martin Gander, Laurence Halpern, Frédéric Magoulès, Francois Roux (2007)

International Journal of Applied Mathematics and Computer Science

Patch substructuring methods are non-overlapping domain decomposition methods like classical substructuring methods, but they use information from geometric patches reaching into neighboring subdomains condensated, on the interfaces to enhance the performance of the method, while keeping it non-overlapping. These methods are very convenient to use in practice, but their convergence properties have not been studied yet. We analyze geometric patch substructuring methods for the special case of one...

Approximation and eigenvalue extrapolation of Stokes eigenvalue problem by nonconforming finite element methods

Shanghui Jia, Hehu Xie, Xiaobo Yin, Shaoqin Gao (2009)

Applications of Mathematics

In this paper we analyze the stream function-vorticity-pressure method for the Stokes eigenvalue problem. Further, we obtain full order convergence rate of the eigenvalue approximations for the Stokes eigenvalue problem based on asymptotic error expansions for two nonconforming finite elements, Q 1 rot and E Q 1 rot . Using the technique of eigenvalue error expansion, the technique of integral identities and the extrapolation method, we can improve the accuracy of the eigenvalue approximations.

Approximation of an eigenvalue problem associated with the Stokes problem by the stream function-vorticity-pressure method

Wei Chen, Qun Lin (2006)

Applications of Mathematics

By means of eigenvalue error expansion and integral expansion techniques, we propose and analyze the stream function-vorticity-pressure method for the eigenvalue problem associated with the Stokes equations on the unit square. We obtain an optimal order of convergence for eigenvalues and eigenfuctions. Furthermore, for the bilinear finite element space, we derive asymptotic expansions of the eigenvalue error, an efficient extrapolation and an a posteriori error estimate for the eigenvalue. Finally,...

Approximation of solution branches for semilinear bifurcation problems

Laurence Cherfils (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

This note deals with the approximation, by a P1 finite element method with numerical integration, of solution curves of a semilinear problem. Because of both mixed boundary conditions and geometrical properties of the domain, some of the solutions do not belong to H2. So, classical results for convergence lead to poor estimates. We show how to improve such estimates with the use of weighted Sobolev spaces together with a mesh “a priori adapted” to the singularity. For the H1 or L2-norms, we...

Approximation of the arch problem by residual-free bubbles

A. Agouzal, M. El Alami El Ferricha (2001)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

We consider a general loaded arch problem with a small thickness. To approximate the solution of this problem, a conforming mixed finite element method which takes into account an approximation of the middle line of the arch is given. But for a very small thickness such a method gives poor error bounds. the conforming Galerkin method is then enriched with residual-free bubble functions.

Approximation of the arch problem by residual-free bubbles

A. Agouzal, M. El Alami El Ferricha (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

We consider a general loaded arch problem with a small thickness. To approximate the solution of this problem, a conforming mixed finite element method which takes into account an approximation of the middle line of the arch is given. But for a very small thickness such a method gives poor error bounds. the conforming Galerkin method is then enriched with residual-free bubble functions.

Approximation of viscosity solution by morphological filters

Denis Pasquignon (2010)

ESAIM: Control, Optimisation and Calculus of Variations

We consider in ℝ 2 all curvature equation ∂ u ∂ t = | D u | G ( curv ( u ) ) where G is a nondecreasing function and curv(u) is the curvature of the level line passing by x. These equations are invariant with respect to any contrast change u → g(u), with g nondecreasing. Consider the contrast invariant operator T t : u o → u ( t ) . A Matheron theorem asserts that all contrast invariant operator T can be put in a form ( T u ) ( 𝐱 ) = inf B ∈ ℬ sup 𝐲 ∈ B u ( 𝐱 + 𝐲 ) . We show the asymptotic equivalence of both formulations. More precisely, we show that all curvature equations can be obtained...

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