Turbulent unsteady separated flows in multidisciplinary computational fluid dynamics applications
Notice bibliographique
Résumé
Employing the advectionâdiffusionâreaction equation as a model problem, a multiscale stable finite element formulation is presented for the SpalartâAllmaras turbulence model, and for the Zonal Detached-Eddy Simulation (ZDES) with a vorticity-based subgrid length scale. The multiscale method arises from a decomposition of the scalar field into coarse (resolved) and fine (unresolved) scales. Modeling of the unresolved scales corrects the lack of stability of the standard Galerkin formulation. The proposed method possesses superior properties like those of the Streamline Upwind/Petrov-Galerkin method and the Galerkin/Least-Squares method. The stabilization terms appear naturally and are effective for turbulent computations in which reaction-dominated effects strongly influence the boundary layer prediction.Validation of the method is accomplished via a two-dimensional problem in which skewed advection goes through a unit square, and a three-dimensional problem where turbulent unsteady flow passes over tandem cylinders. The boundary layer separation, free shear layer roll-up, vortex shedding from the upstream cylinder, and interaction with the downstream cylinder, are well reproduced. Good agreement with experimental measurements gives credence to the accuracy of ZDES in modeling turbulent separated flows.Following validation, two problems related to turbulent flows in aerospace and wind engineering applications are investigated. The first study is the evaluation of the performance degradation of ice-contaminated airfoils, including a NACA 23012 airfoil with a spanwise ice ridge, and a GLC-305 airfoil with a leading edge horn-shape glaze ice. Appropriate spanwise domain size and sufficient grid density are determined to enhance the reliability of the simulations. A comparison of lift coefficient and flow field variables demonstrates the added advantage of the ZDES model for the standard SpalartâAllmaras turbulence model, as illustrated by massively separated flows at pre-stall conditions of an icing airfoil. The vorticity-based subgrid length scale in ZDES prevents the delayed development of instabilities in the shear layer and a subsequent late transition to a fully turbulent flow. Spectral analysis and instantaneous visualization of turbulent structures are also highlighted.Another application of interest is wind-induced vibrations of tall buildings. In this numerical procedure, the natural unsteady wind in the atmospheric boundary layer is modeled with artificial inflow turbulence generation. The turbulent flow is simulated by the stabilized ZDES model, and a conservative quadrature-projection scheme is adopted to transfer unsteady loads from fluid to structural nodes. The aerodynamic damping that represents the fluid-structure interaction mechanism is determined by empirical functions extracted from wind tunnel experiments. Eventually, the unsteady motion of the building is solved via a structural modal analysis. The flow solutions and the structural responses in terms of mean and root mean squared quantities are compared with experimental measurements, over a wide range of reduced velocities. The significance of turbulent inflow conditions and aeroelastic effects is highlighted. This numerical procedure provides predictions of good accuracy and can be considered a preliminary design tool to evaluate unsteady wind effects on tall buildings.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».