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 38 for “"vortex ring"”.
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Vortex Ring Collision with Free-Slip and No-Slip Wall
Vortex ring collision on wall explains azimuthal instability, stretching, vorticity and wall turbulence in a simplified way, required in many applications. Present study performs high Reynolds number (2500 and 4000) simulations of vortex rings approaching no-slip and free-slip walls for different …
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Measurements of Small-Scale Propellers Operating in the Vortex Ring State
… operating in vertical descent and through the vortex ring state (VRS) was measured. In particular, a total of 26 propellers with varying diameters (9 to 11 in) were tested in the UIUC 2.8 x 4 ft wind tunnel at low Reynolds numbers to measure the propeller thrust over a range of advance ratios …
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A numerical study of laminar to turbulent evolution and free-surface interaction of a vortex ring
… simulation was used to study various aspects of vortex ring evolution and interaction with a free surface. An investigation of a single unbounded vortex ring at various Reynolds numbers and core thicknesses showed qualitative differences between the evolution of thin- and thick-core rings, …
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Study of Vortex Ring Dynamics in the Nonlinear Schrödinger Equation Utilizing GPU-Accelerated High-Order Compact Numerical Integrators
… study the dynamics and interactions of vortex rings in the nonlinear Schrödinger equation (NLSE). Single ring dynamics for both bright and dark vortex rings are explored including their traverse velocity, stability, and perturbations resulting in quadrupole oscillations. Multi-ring …
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On vortex rings impacting a sharply-stratified interface
… presents an investigation into the dynamics of vortex rings impacting a sharply-stratified density interface. This problem has a long history and is important for understanding how individual eddies in stratified turbulence mix the density field. We tackle this problem using a combination of …
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An experimental study of turbulent vortex rings using particle image velocimetry
… dissertation, the early development of turbulent vortex rings at two Reynolds numbers is studied using two-dimensional and Stereoscopic Particle Image Velocimetry. In the late 1980s’ a similarity theory of turbulent vortex rings was proposed and tested primarily using a twochannel tracking Laser …
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AirTap : a multimodal interactive interface platform with free-space cutaneous haptic feedback via toroidal air-vortices
… technologies, which are now capable of delivering rich and highly immersive experiences, the need has arisen to develop equally capable haptic-feedback technologies that can complement and be easily integrated with their visual counterparts to enable fully immersive, multimodal, interactive …
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On quantum vortex reconnections
… we study the reconnection between an inclined vortex ring and a straight vortex line, where the vortex ring inclination angle is varied. We analyze the evolution throughout the dynamics of the total length and curvature of the vortex filaments for different values of the inclination angle, as …
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Hydrodynamics of Cardiac Diastole
… work includes studies of in-vivo and in-vitro vortex rings. Vortex rings created in the left ventricle past the mitral valve during diastole are produced in a confined domain and are influenced by the left ventricular walls. Therefore, an in-vitro analysis of the formation and decay of vortex …
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Characteristics of the High Speed Gas-Liquid Interface
… supercavity is governed by the formation of a vortex ring. Nuclei are shed from the forebody of the accelerating projectile and are entrained in the vortex ring core where they are subjected to low pressure and subsequently expand rapidly. A characteristic time scale for this supercavity …
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Anti-Predator Responses of Squid Throughout Ontogeny
… (3) document how chromatic patterning, posturing and inking in squid change in response to predators; and (4) investigate escape jet hydrodynamics of squid. Given that squids undergo considerable morphological, ecological, and behavioral changes throughout ontogeny, the goals above were all …
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Laminar Analogues of Atmospheric Phenomena
… determining the final properties of the buoyant vortex ring that is produced, with thermals displaying an independence above a critical Reynolds number. Another notable observation is that the wake left behind by the first vortex ring can itself roll up to form a second ring that follows after …
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Design of miniature floating platform for marginal fields
… optimization. A self-developed model "Discrete Vortex Ring Model" (DVRM) to efficiently estimate the viscous drag due to the vortex shedding of the oscillatory heave plate is presented in details. This new model DVRM combined with the standard radiation/diffraction code WAMIT is used to analyse …
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Helicopter Flight Dynamics Simulation with a Time-Accurate Free-Vortex Wake Model
… simulation model with a time-accurate free-vortex wake model capable of capturing the response to maneuvers of arbitrary amplitude. The resulting model has been used to analyze different flight conditions, including both steady and transient maneuvers. The flight dynamics model is based on a …
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An Investigation of the Irrotational Near Field of an Excited High Speed Jet.
… This is indicative of a large-scale structure (a vortex ring) that is generated by each impulsively seeded perturbation. The signature of these large-scale structures is shown to rapidly decay with radial distance from the jet. Simultaneous measurements of acoustic far field were also performed …
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Numerical and analytical studies of single and multiphase starting jets and plumes
… plumes are widely observed in nature and engineering systems. An environmental engineering example is open-water disposal of sediments. The present study numerically simulates such starting jets/plumes using Large Eddy Simulations. The numerical scheme is first validated for single phase plumes, …
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Linear stability analysis of circular jets: integer, fractional, and multiple mode excitation
… modes were found to result in un-even, periodic, vortex-ring growth in the shear layer. An argument was presented for the axisymmetric mode (m=O) resulting in the highest levels of entrainment for all integer, fractional, and multiple modes of excitation. Finally the importance of the azimuthal …
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Non-linear, non-spherical bubble dynamics near a two fluid interface
… integral implementation coupled with the vortex ring toroidal bubble model [53]. The transition through the null impulse state has been investigated, demonstrating excellent agreement with the water/white spirit experiments of Chahine and Bovis [23]. Close standoff distance simulations …
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Form, function and flow in the plankton : jet propulsion and filtration by pelagic tunicates
… Small-scale particle encounter at the salp filtering apparatus was also explored. Observations and experiments were conducted at the Liquid Jungle Lab, off the pacific coast of Panama in January 2006 through 2009. First, time-varying body volume was calculated by digitizing salp outlines from in …
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