By applying pattern recognition analysis, the organised eddy structures in the near and intermediate fields (10-40 jet diameters) of a numerically simulated turbulent plane jet have been investigated. The Reynolds number based on the jet width is 1, 600. The results of the nearly full simulation show good agreement with the experimental measurements in the near and intermediate regions (< 40 diameters) of the jet. Patterns of organised eddy structures have been extracted from the three-dimensional simulation databases. Ensemble averaged fields of three velocity components and pressure in the spanwise and transverse planes suggest the existence of inclined vortex pairs. These highly three-dimensional vortical structures are confined to one side of the jet centreplane and approximately align with the principal axis of rate-of-strain. Some of the topological features of these averaged eddy structures have been examined.

In this study the complete four dimensional space time correlation function was measured in the wake of an untripped circular cylinder at a Reynolds number of 60 000. This correlation serves as the complete inflow boundary condition for an open rotor ingesting inhomogeneous turbulence. An important aspect of the turbulence ingestion problem is understanding how different inflow boundary conditions effect the sound produced by a rotor. In the present study the turbulence structure of two plane wakes were compared. Measurements completed by a previous study in the wake of a NACA 0012 airfoil were compared with the measurements completed by the present study in the wake of a cylinder. The mean flows of both plane wakes were found to be very similar, however the Reynolds stress profiles show that the cylinder wake is substantially more turbulent. The structures of the two-point correlation function in each wake are also similar, although the cylinder wake had greater maximum correlation values and was correlated at greater separations. The two-point correlation was used along with proper orthogonal decomposition to compute the average instantaneous velocity fields of both wake flows. These velocity fields represent the average eddy structures present in each wake flow. The eddy structure comparisons show that the structures in the cylinder wake are larger and better correlated at longer time delays. / Master of Science

La recherche sur le transport de sédiments dans les réservoirs vise principalement à optimiser la conception du réservoir dans les réseaux d’assainissement. La structure de l'écoulement, qui fait l’objet de cette recherche, représente le facteur principal de contrôle du mouvement des particules et conditionne leur dépôt. Le travail réalisé s’est basé aussi bien sur les méthodes numériques que les essais expérimentaux. La simulation numérique est traitée en utilisant trois géométries différentes, où un volume de modèle de fluide est appliqué pour le suivi de la surface libre et un modèle de phase discrète est utilisé pour calculer la trajectoire des particules, et une fonction définie par l'utilisateur basée sur la courbe de Shields est implémentée comme condition limite pour augmenter les taux de déposition simulés. Des séries d'expériences sont réalisées dans un réservoir rectangulaire avec une cavité, pour mesurer le champ de vitesses dans différentes conditions d’écoulement, et déterminer les zones de dépôts des sédiments au fond du réservoir. La comparaison entre les simulations numériques et les résultats expérimentaux montre une bonne concordance des résultats obtenus pour la prédiction des écoulements et des dépôts. L'amélioration du dépôt de particules nécessite une modification supplémentaire du modèle de suivi des particules. / The investigation on sediment transport in tanks is mainly for optimizing the design of tank in stormwater system and sewers. The flow pattern is the primary factor controlling the movement of particle. Therefore, the emphasis of this investigation is to determine the flow pattern and estimate the deposition of particle. Both computational fluid dynamics and experimental methods are applied to accomplish the research. Numerical simulation are processed by using three different geometries, where a volume of fluid model is applied for tracking the free-surface and a discrete phase model is used for calculation of particle trajectory, and an user defined function based on Shields curve is implemented to the boundary for improving the simulation on sedimentation. A series of experiments are carried out in a rectangular tank with a cavity, where velocity measurements are finished for experiments under different conditions and the sediment deposition is recorded. The comparison between numerical simulation and experimental results show better agreement in the prediction of flow, the improvement on particle deposition needs further modification in the particle tracking model.