Turbulent flows present structures with a wide range of scales. The computation of the complete physics of a turbulent flow (termed DNS) is very expensive and is, for the time being, limited to low and medium Reynolds number flows. As a way to capture high Reynolds number flows, a part of the physics complexity has to be modeled. Large eddy simulation (LES) is a simulation strategy where the large turbulent eddies present on a given mesh are captured and the influence of the non-resolved scales onto the resolved ones is modeled. The present thesis reports on the development and validation of a methodology in order to apply LES for complex wall-bounded flows. Discretization methods and LES models, termed subgrid scale models (SGS), compatible with such a geometrical complexity are discussed. It is proved that discrete a kinetic energy conserving discretization of the convective term is an attractive solution to perform stable simulations without the use of an artificial dissipation, as upwinding. The dissipative effect of the SGS model is thus unaffected by any additional dissipation process. The methodology is first applied to a developed parallel fourth-order incompressible flow solver for cartesian non-uniform meshes. In order to solve the resulting Poisson equation, an efficient multigrid solver is also developed. The code is first validated using DNS (Taylor-Green vortex, channel flow, four-vortex system) and LES (channel flow), and finally applied to the investigation of an aircraft two-vortex system in ground effect. The methodology is then applied to improve a RANS-based industrial unstructured compressible flow solver, developed at CENAERO, to perform well for LES applications. The proposed modifications are tested successfully on the unsteady flow past a sphere at Reynolds of 300 and 10000, corresponding to the subcritical regime.
| Identifer | oai:union.ndltd.org:BICfB/oai:ucl.ac.be:ETDUCL:BelnUcetd-05302007-181055 |
| Date | 12 June 2007 |
| Creators | Georges, Laurent |
| Publisher | Universite catholique de Louvain |
| Source Sets | Bibliothèque interuniversitaire de la Communauté française de Belgique |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-05302007-181055/ |
| Rights | unrestricted, J'accepte que le texte de la th�se (ci-apr�s l'oeuvre), sous r�serve des parties couvertes par la confidentialit�, soit publi� dans le recueil �lectronique des th�ses UCL. A cette fin, je donne licence � l'UCL : - le droit de fixer et de reproduire l'oeuvre sur support �lectronique : logiciel ETD/db - le droit de communiquer l'oeuvre au public Cette licence, gratuite et non exclusive, est valable pour toute la dur�e de la propri�t� litt�raire et artistique, y compris ses �ventuelles prolongations, et pour le monde entier. Je conserve tous les autres droits pour la reproduction et la communication de la th�se, ainsi que le droit de l'utiliser dans de futurs travaux. Je certifie avoir obtenu, conform�ment � la l�gislation sur le droit d'auteur et aux exigences du droit � l'image, toutes les autorisations n�cessaires � la reproduction dans ma th�se d'images, de textes, et/ou de toute oeuvre prot�g�s par le droit d'auteur, et avoir obtenu les autorisations n�cessaires � leur communication � des tiers. Au cas o� un tiers est titulaire d'un droit de propri�t� intellectuelle sur tout ou partie de ma th�se, je certifie avoir obtenu son autorisation �crite pour l'exercice des droits mentionn�s ci-dessus. |
Page generated in 0.0023 seconds