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 28 for “"vortex rings"”.
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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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The dynamics and mixing properties of vortex rings obliquely impacting a density interface
… into the dynamics and mixing properties of vortex rings obliquely impacting the density interface in a two-layer density stratification. For turbulent two-layer zero-mean-shear flows, the classical grid-mixing experiments of J.S. Turner (J. Fluid. Mech, 33:639–656, 1968) demonstrated the …
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Experimental investigation of vortex rings and helicopter rotor wakes using a laser Doppler velocimeter,
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1973.
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THE EFFECT OF RAIN ON INTERTIDAL ESTUARINE SEDIMENT TRANSPORT (VORTEX RINGS, OXYGENATION, DROP/SPLASH FEATURES, FECAL PELLETS)
… of motion of sediment. Results indicate single vortex rings in a quiescent environment can initiate motion of sand-sized noncohesive sediment in all water depths tested, up to and including 22.5 cm. Multidrop experiments (with estuarine muds) indicated that rain can resuspend cohesive sediment …
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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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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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Volumetric analysis of fish swimming hydrodynamics using synthetic aperture particle image velocimetry
… used to characterize the size and shape of the vortex rings shed by the fish during forward swimming and turning. Results show clearly isolated and linked vortex rings in the wake structure, as well as the thrust jet coming off of a visual hull reconstruction of the fish body. Depending on the …
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Modeling, design, and fabrication of pulsed fluidic micro-actuators
… and amplitudes of vibration, a streaming of vortex rings can occur near the orifice. These vortex rings move under their own self-induced momentum. Downstream of the opening the rings ultimately break up and can form a fully developed jet. This work is dedicated to the analysis, design, and …
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Vortex dynamics and forces in the laminar wakes of bluff bodies
Coherent vortex-dominated structures in the wake are ubiquitous in natural and engineered flows. The well-known 'von Karman street', in which two rows of counter-rotating vortices develop on the leeward side of a solid body immersed in a fluid, is only one such vortex-based structure in the wake. …
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Near field behavior of reacting free jets
… elliptical jet exhibited out-of-plane vortex dynamics and subsequently, structure merging primarily contained within the minor axis region. Chemical reaction hindered out-of-plane vortex motion causing the reacting jet to form primarily planar vortex rings. The overall structure and …
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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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Many-body physics and non-equilibrium dynamics in ultracold atomic systems
… experiments are unstable to the formation of vortex rings; the second demonstrates how population imbalance between up and down spin fermions can be used to prevent this instability. In the next study I discuss a method for generating and probing topologically protected edge states using …
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The Influence of Trailing Edge Shape and Kinematics on Bio-inspired Pitching Panels
… comprised of a series of connected, alternating vortex rings that are comprised of spanwise and streamwise vortices. The influence of these vortex rings are their induced velocity fields are highly dependent on Strouhal number and panel geometry, with increases in Strouhal number and trailing …
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The evolution of vortices in a turbulent boundary layer
… this investigation, the evolution of a perturbed vortex tube near a boundary is examined in order to gain insight into turbulent boundary layer phenomena. A Lagrangian vortex model is used to describe the vortex tube evolution, including the influence of shear. Based on numerical calculations, it …
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Understanding Vortex Reconnection in Complex Fluid Flows
… the reconnection process for three initial vortex tube set-ups; anti-parallel, orthogonal and anti-parallel with axial flow. From these we are able to identify each of the different reconnection processes observed and discussed for the magnetic reconnection case but not necessarily the …
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Quantized vortices in arbitrary dimensions and the normal-to-superfluid phase transition
… and asymptotically large, compared with the vortex core size. The motion of vortices is analyzed in general, as well as for the special cases of hyper-spherical and weakly distorted hyper-planar vortices. In all dimensions, vortex motion reflects vortex geometry. In dimension four and higher, …
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Numerical simulation of the flow in model skeletal muscle ventricles
… feature of these flows is the formation of vortex rings. Vortices enhance mixing, and this is a useful process to encourage in an SMV, as it could assist in the mixing of the blood components and in the reduction of apical residence time. Being able to predict accurately the dynamics of the …
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Analytical Unsteady Aerodynamic Models for Horizontal Axis Wind Turbines
… test data. The unsteady wake is modeled using vortex methods. The analysis covers unsteady loading due to fast pitch change at constant wind speed, and varying wind speed at constant pitch. The analysis can be extended to more complex conditions. The work starts by modeling dynamic inflow …
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Cluster Weather Vanes: Radio Galaxies as Indicators of Galaxy Cluster Dynamics
… cocoons produce vorticity which can result in a vortex ring, possibly disrupting the jet and creating a distinct ring structure. These rings can remain visible for significant time due to magnetic field amplification, but if they are overlapping active jets in projection, the emission from the …
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