Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 50 for “"Vortex Formation"”.
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Separation Bubbles and Vortex Formation in Cavity Flows
… is a computational fluid dynamic study of the formation of vortices and separation bubbles in a square cavity as well as in a cylindrical cavity. Whereas there has been previous research work on the problem of a free stream over different types of cavities, like open and closed cavities or lid …
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Studies in Tip Vortex Formation, Evolution and Control
… equations. This methodology is used to study the formation and evolution of tip vortices from fixed wings and rotary blades. The numerical error is reduced by using high order accurate schemes on appropriately refined meshes. For vortex evolution problems, the equations are solved on multiple {\em …
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Effect of Endwall Fluid Injection on Passage Vortex formation in a First Stage Nozzle Guide Vane Passage
… junction. The effect of the secondary jet on the formation of the leading edge horseshoe vortex and the consequent formation of the passage vortex has been studied. For the computations, the Reynolds averaged Navier–Stokes (RANS) equations were solved with the commercial software ANSYS Fluent …
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Vortex Induced Vibrations of cylinders : experiments in reducing drag force and amplitude of motion
Reducing the deleterious effect of Vortex Induced Vibrations (VIV) in marine risers is an important task for ocean engineers; and many competing factors exist in the design of VIV suppression devices. This thesis explores the experimental minimization of the drag force and the disruption of vortex …
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Computational and experimental study of trailing vortices
… trailing from low aspect ratio lifting surfaces. Vortex formation in the near-wake was measured in a wind tunnel with yaw-head and hot-wire probes at three different Reynolds numbers, the highest of which was greater than most previous studies. These near-wake measurements provided initial …
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Two-dimensional Wakes and Fluid-structure Interaction of Circular Cylinders in Cross-flow
… of a bluff body is a representative issue in vortex dynamics that plays a central role in civil engineering, ocean engineering and thermal engineering. In this work, a flowing soap film was used to investigate the wakes of multiple stationary circular cylinders and of a single oscillating …
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Flow Around Cambered and Yawed Pneumatic Tyres
… are presented showing a detailed view of the formation process of vortices generated on the front and rear surfaces of the tyre near the ground, and their downstream behaviour. This data informs discussion of an updated model of the vortex lines around the lower half of the tyre. Using a new …
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Kinematic and vortical wake patterns of rapidly maneuvering fish and flapping foils
… order to gain a first order understanding of the vortex formation in a simple biomimetic device.
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A Comparative In Vitro Study of the Flow Characteristics Distal to Mechanical and Natural Mitral Valves
… maps are presented, which provide detailed information about the development of the flow. Time-averaged velocity, vorticity, and turbulent kinetic energy measurements are also discussed. Asynchronous leaflet behavior was observed in all cases involving the mechanical valve. Extensive vortex …
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Radar observations of misovortices within multiple long-lake-axis-parallel lake-effect bands during the OWLeS project
… shear along these convergence zones yields vortex sheets that can break into discrete misovortices, likely through horizontal shearing instability (HSI). These misovortices then can strengthen or be maintained via stretching by the band updrafts. Recent analysis of a single case from OWLeS …
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Unsteady Viscous Cavity Flow Using Computational Fluid Dynamics
… the appearance of separation bubbles and vortex formation inside the cavity. Steady state flows are also obtained from the unsteady simulations after convergence of the time dependent solutions. Then the case of a cavity with a synthetic jet and two outlets is treated, where a complex …
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Numerical studies of unsteady flow past bluff bodies
… at Reynolds numbers up to 1000 to study onset of vortex shedding and early stages of flow evolution. Loads have been calculated for the trapezoid section by solving Poisson equation for total pressure and its connection to the generation of unsteadiness has been explained. In addition, flows past …
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BOUNDARY LAYER ON FLAT PLATE WITH LEADING EDGE PATTERNS
… EFFECT OF THE AMPLITUDE AND WAVELENGTH ON THE VORTEX STRUCTURE WAS STUDIED FOR THE TRIANGULAR LEADING EDGE. IT WAS FOUND THAT STREAMWISE COUNTER-ROTATING VORTICES IN THE FORM OF MUSHROOM-LIKE STRUCTURES INITIATED FROM THE TROUGH OF THE PATTERNS. THE NUMBER OF THE PRESET VORTICES WAS EQUAL TO …
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Effect of latent heating on mesoscale vortex development during extreme precipitation: Colorado, September 2013
… From 0400-0700 UTC 12 September, a mesoscale vortex (mesovortex) was observed to travel northwestward towards Boulder. This circulation enhanced upslope flow and was associated with localized deep convection. The mesovortex originated in an area common for the development of a lee vortex known …
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Effect of diameter ratios on the flow-sound interaction of the straight circular finned cylinders
… showed that the temporal evolution of the vortex shedding in the wake becomes more periodic when the diameter ratio of the finned cylinders (Df =Dr) increases. Moreover, the strength of the vortices increases significantly in the wake. The increase in the flow entrainment in between the …
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A secondary flow approach to the inlet vortex flow field
… is presented of the fluid mechanics of the inlet vortex (or ground vortex) phenomenon. The vorticity field associated with the vortex is investigated using a secondary flow approach. In this approach the flow is assumed to be composed of an irrotational primary flow and a weak shear flow, with the …
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Flow study of the nozzle region of the space shuttle solid rocket motor
… and recirculation flows around the nozzle. Vortex formation near the nozzle inlet was also observed and was the prime focus of this investigation. Because the nozzle inlet geometry was very similar to an aircraft engine inlet operating close to the ground, vortices seen in this investigation …
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Turbulent Molecular Mixing in Gaseous Free Shear Flows
… three main stages of shear layer development. Vortex mixing in the near field of an axisymmetric jet (ReD = 2300) is studied by using an acoustic pulse to obtain repeatable vortex formation and merging events. Results indicate that the mixing process is initially slow within the laminar vortex …
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Modelling local scour around bridge piers using TELEMAC
… types is local scour which occurs as a result of vortex formation around bridge piers and abutments (Hoffmans & Verheij, 1997; Raudkivi, 1998; Melville & Coleman, 2000; Richardson & Davis, 2001; Armitage & McGahey, 2003). Local scour is also one of the most difficult to predict accurately. If not …
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Effect of spillway-ogee location on flow uniformity and turbulence at the crest of an ogee weir
… affects flow uniformity and possible shed-vortex formation from the intake abutment. Therefore, the results also indicate that spillway crest location has a direct impact on the hydraulic performance of the spillway. Suitable selection of crest location can be used to minimize …
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