Reliable Methods for Computer Simulation - Error Control and A Posteriori Estimates

2004 ◽  
Keyword(s):  
Computer Simulation ◽  
Error Control ◽  
A Posteriori ◽  
A Posteriori Estimates ◽  
Simulation Error ◽  
Reliable Methods

A Posteriori Error Control at Numerical Solution of Plate Bending Problem

2015 ◽  
Vol 725-726 ◽  
pp. 674-680
Author(s):  
V.G. Korneev
Keyword(s):  
Error Control ◽  
Variational Principles ◽  
Posteriori Error ◽  
Mechanics Of Solids ◽  
Plate Bending ◽  
A Posteriori ◽  
A Posteriori Error ◽  
Elasticity Equations ◽  
A Posteriori Estimates ◽  
Thin Plate Bending

The classical approach to a posteriori error control considered in this paper bears on the counter variational principles of Lagrange and Castigliano. Its efficient implementation for problems of mechanics of solids assumes obtaining equilibrated stresses/resultants which, at the same time, are sufficiently close to the exact values. Besides, it is important that computation of the error bound with the use of such stresses/resultants would be cheap in respect to the arithmetic work. Following these guide lines, we expand the preceding results for elliptic partial differential equations and theory elasticity equations upon the problem of thin plate bending. We obtain guaranteed a posteriori error bounds of simple forms for solutions by the finite element method and discuss the algorithms of linear complexity for their computation. The approach of the paper also allows to improve some known general a posteriori estimates by means of arbitrary not equilibrated stress fields.

scholarly journals Functional A Posteriori Error Control for Conforming Mixed Approximations of Coercive Problems with Lower Order Terms

2016 ◽  
Vol 16 (4) ◽  
pp. 609-631 ◽  
Author(s):  
Immanuel Anjam ◽  
Dirk Pauly
Keyword(s):  
Error Control ◽  
A Posteriori Error Estimates ◽  
Reaction Diffusion ◽  
Posteriori Error ◽  
Diffusion Problem ◽  
Mixed Formulation ◽  
A Posteriori ◽  
A Posteriori Error ◽  
Linear Partial Differential Equations ◽  
Primal And Dual

AbstractThe results of this contribution are derived in the framework of functional type a posteriori error estimates. The error is measured in a combined norm which takes into account both the primal and dual variables denoted by x and y, respectively. Our first main result is an error equality for all equations of the class ${\mathrm{A}^{*}\mathrm{A}x+x=f}$ or in mixed formulation ${\mathrm{A}^{*}y+x=f}$, ${\mathrm{A}x=y}$, where the exact solution $(x,y)$ is in $D(\mathrm{A})\times D(\mathrm{A}^{*})$. Here ${\mathrm{A}}$ is a linear, densely defined and closed (usually a differential) operator and ${\mathrm{A}^{*}}$ its adjoint. In this paper we deal with very conforming mixed approximations, i.e., we assume that the approximation ${(\tilde{x},\tilde{y})}$ belongs to ${D(\mathrm{A})\times D(\mathrm{A}^{*})}$. In order to obtain the exact global error value of this approximation one only needs the problem data and the mixed approximation itself, i.e., we have the equality$\lvert x-\tilde{x}\rvert^{2}+\lvert\mathrm{A}(x-\tilde{x})\rvert^{2}+\lvert y-% \tilde{y}\rvert^{2}+\lvert\mathrm{A}^{*}(y-\tilde{y})\rvert^{2}=\mathcal{M}(% \tilde{x},\tilde{y}),$where ${\mathcal{M}(\tilde{x},\tilde{y}):=\lvert f-\tilde{x}-\mathrm{A}^{*}\tilde{y}% \rvert^{2}+\lvert\tilde{y}-\mathrm{A}\tilde{x}\rvert^{2}}$ contains only known data. Our second main result is an error estimate for all equations of the class ${\mathrm{A}^{*}\mathrm{A}x+ix=f}$ or in mixed formulation ${\mathrm{A}^{*}y+ix=f}$, ${\mathrm{A}x=y}$, where i is the imaginary unit. For this problem we have the two-sided estimate$\frac{\sqrt{2}}{\sqrt{2}+1}\mathcal{M}_{i}(\tilde{x},\tilde{y})\leq\lvert x-% \tilde{x}\rvert^{2}+\lvert\mathrm{A}(x-\tilde{x})\rvert^{2}+\lvert y-\tilde{y}% \rvert^{2}+\lvert\mathrm{A}^{*}(y-\tilde{y})\rvert^{2}\leq\frac{\sqrt{2}}{% \sqrt{2}-1}\mathcal{M}_{i}(\tilde{x},\tilde{y}),$where ${\mathcal{M}_{i}(\tilde{x},\tilde{y}):=\lvert f-i\tilde{x}-\mathrm{A}^{*}% \tilde{y}\rvert^{2}+\lvert\tilde{y}-\mathrm{A}\tilde{x}\rvert^{2}}$ contains only known data. We will point out a motivation for the study of the latter problems by time discretizations or time-harmonic ansatz of linear partial differential equations and we will present an extensive list of applications including the reaction-diffusion problem and the eddy current problem.

Local A Posteriori Estimates on a Nonconvex Polygonal Domain

2012 ◽  
Vol 50 (2) ◽  
pp. 906-924 ◽  
Author(s):  
JaEun Ku ◽  
Alfred H. Schatz
Keyword(s):  
Polygonal Domain ◽  
A Posteriori ◽  
A Posteriori Estimates

scholarly journals On a posteriori estimates for a linearized Oldroyd's problem

2004 ◽  
Vol 167 (2) ◽  
pp. 345-361 ◽  
Author(s):  
K. Najib ◽  
D. Sandri ◽  
A.-M. Zine
Keyword(s):  
A Posteriori ◽  
A Posteriori Estimates

scholarly journals A Posteriori Estimates for Conforming Kirchhoff Plate Elements

2018 ◽  
Vol 40 (3) ◽  
pp. A1386-A1407 ◽  
Author(s):  
Tom Gustafsson ◽  
Rolf Stenberg ◽  
Juha Videman
Keyword(s):  
Kirchhoff Plate ◽  
A Posteriori ◽  
Plate Elements ◽  
A Posteriori Estimates
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