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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Nonconforming formulations with spectral element methods

Sert, Cuneyt 15 November 2004 (has links)
A spectral element algorithm for solution of the incompressible Navier-Stokes and heat transfer equations is developed, with an emphasis on extending the classical conforming Galerkin formulations to nonconforming spectral elements. The new algorithm employs both the Constrained Approximation Method (CAM), and the Mortar Element Method (MEM) for p-and h-type nonconforming elements. Detailed descriptions, and formulation steps for both methods, as well as the performance comparisons between CAM and MEM, are presented. This study fills an important gap in the literature by providing a detailed explanation for treatment of p-and h-type nonconforming interfaces. A comparative eigenvalue spectrum analysis of diffusion and convection operators is provided for CAM and MEM. Effects of consistency errors due to the nonconforming formulations on the convergence of steady and time dependent problems are studied in detail. Incompressible flow solvers that can utilize these nonconforming formulations on both p- and h-type nonconforming grids are developed and validated. Engineering use of the developed solvers are demonstrated by detailed parametric analyses of oscillatory flow forced convection heat transfer in two-dimensional channels.
2

Nonconforming formulations with spectral element methods

Sert, Cuneyt 15 November 2004 (has links)
A spectral element algorithm for solution of the incompressible Navier-Stokes and heat transfer equations is developed, with an emphasis on extending the classical conforming Galerkin formulations to nonconforming spectral elements. The new algorithm employs both the Constrained Approximation Method (CAM), and the Mortar Element Method (MEM) for p-and h-type nonconforming elements. Detailed descriptions, and formulation steps for both methods, as well as the performance comparisons between CAM and MEM, are presented. This study fills an important gap in the literature by providing a detailed explanation for treatment of p-and h-type nonconforming interfaces. A comparative eigenvalue spectrum analysis of diffusion and convection operators is provided for CAM and MEM. Effects of consistency errors due to the nonconforming formulations on the convergence of steady and time dependent problems are studied in detail. Incompressible flow solvers that can utilize these nonconforming formulations on both p- and h-type nonconforming grids are developed and validated. Engineering use of the developed solvers are demonstrated by detailed parametric analyses of oscillatory flow forced convection heat transfer in two-dimensional channels.
3

Méthode des éléments finis avec joints en recouvrement non-conforme de maillages : application au contrôle non destructif par courants de Foucault / Mortar finite element method with overlapping non-matching grids : application of eddy current non-destructive testing

Christophe-Argenvillier, Alexandra 24 November 2014 (has links)
Cette thèse vise à développer et à évaluer une méthode de décomposition de domaine avec recouvrement dans le cadre de la modélisation du contrôle non destructif (CND) par courants de Foucault (CF). L'objectif d'une telle approche consiste à éviter le remaillage systématique de l'intégralité du domaine d'étude lors du déplacement de l'un de ses éléments constitutifs(par exemple, déplacement de la sonde CF au dessus de la pièce contrôlée). Plus précisément, il s'agit de concevoir une méthode de décomposition de domaine avec recouvrement qui s'appuie sur la théorie apportée par la méthode des éléments finis avec joints. En plus de s'affranchir de la contrainte d'une interface d'échange invariante avec le mouvement, la technique décrite dans ce travail réalise des transferts d'information réciproques entre les domaines. Cette étude présente les résultats théoriques ainsi que numériques liés à la simulation magnétodynamique. Par ailleurs, l'intérêt d'une telle méthode est illustré par des applications sur des configurations bidimensionnelles de CND par CF. / This thesis aims at studying and developing a domain decomposition method with overlapping subdomains for the modeling in eddy current (EC) non-Destructive testing (NDT). The idea behind such an approach is the possibility to avoid the systematic remeshes of the whole studying domain when some of its components are modified (for example the displacement of the coil above the conductor). More precisely, this work aims at designing a domain decomposition method with overlapping based on the theory of the mortar finite element method. In addition to remove the constraint owing to an coupling interface which is invariant with the displacement, the technique described, in this work, realizes reciprocal transfers of information between subdomains. This study presents the theoretical and numerical results attached to the magnetodynamic simulation. Moreover, the interest of such a method is illustrated by applications in some 2D modeling cases of EC NDT.

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