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 23 for “"Vortex stretching"”.
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MECHANISMS FOR THE EXISTENCE OF DIAGONAL SOUTHERN HEMISPHERE CONVERGENCE ZONES
… and upper-tropospheric divergence; through vortex stretching this leads to an anticyclonic vorticity tendency. The calculation of a vorticity budget shows this tendency is strong enough to dissipate the wave. A similar sequence of events triggers diagonal bands of convection in the SACZ, …
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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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Overflows and upper ocean interactions : a mechanism for the Azores current
… The upper ocean must balance the mass loss and vortex stretching associated with entrainment. Thus for the upper ocean, overflows represent a localized region of intense mass and PV forcing. The simulations in this study show that in the upper layer, entrainment forces a cyclonic circulation …
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The adjustment of barotropic currents at the shelf break to a sharp bend in the shelf topography
… vorticity dynamics allow a balance between the vortex stretching in the flow and the curvature in the flow. This is possible since the bend is a right-hand one facing downstream, a similar balance not being possible for a left-hand bend, in which case eddy formation is likely. A simple model of …
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Agulhas retroflection rings in the South Atlantic Ocean
… The deep stad is shown to be likely due to vortex stretching and possible sources for the water in the stad are suggested. Comparative hydrographic characteristics, water mass structure, velocity fields, and the potential for contribution to interbasin transfer of the three rings are …
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Submesoscale eddies and their potential for buoyant microplastic accumulation
… of its flow and geometry, finding that vortex stretching dominates the vorticity equation, the elliptical eddy interior is approximately in cyclogeostrophic balance, and the eddy core is approximately in rigid body rotation. Upon characterizing this eddy, we transition to studying where …
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Covering Shock Wave Induced Interfacial Mixing: Numerical Study and a Control Primer
… only quickly addressed. The main effect is the vortex stretching affectation on the vorticity evolution. Furthermore, mixing layers in 3D spherical simulations are found to be wider than its 2D simplified framework. Nonetheless, useful insight is gained by reducing the problem under study to a …
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Overflows and upper ocean interaction : a mechanism for the Azores Current
… The upper ocean must balance the mass loss and vortex stretching associated with entrainment. Thus for the upper ocean, overflows represent a localized region of intense mass and PV forcing. The simulations in this study show that in the upper layer, entrainment forces a cyclonic circulation …
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Vortices and Rossby-wave radiation on the beta-plane
… equation. For the nondivergent case, with no vortex stretching, a different dynamical balance holds in the far field. Chapter 2 derives an exact mode-one solution for the radial Rayleigh operator and completely solves the classical inviscid instability initial-value problem for mode-one …
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The structure of a trailing vortex wake
… performed in the spiral wake that surrounds the vortex shed from the tip of a rectangular NACA 0012 half wing. Both single-point and simultaneous two-point hot-wire measurements were made ten chord lengths downstream of the wing at a Reynolds number of 320,000. The structure of this flow consists …
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Moored observations of shelfbreak processes at the inflow to and outflow from the Arctic Ocean
… Seas overflows the Denmark Strait and undergoes vortex stretching, forming intense cyclones that propagate along the East Greenland slope. Data from the mooring array at 65°N—roughly 300 km downstream of Denmark Strait—was used to determine the full water column structure of the cyclones. On …
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Moored observations of shelfbreak processes at the inflow to and outflow from the Arctic Ocean
… Seas overflows the Denmark Strait and undergoes vortex stretching, forming intense cyclones that propagate along the East Greenland slope. Data from the mooring array at 65°N-roughly 300 km downstream of Denmark Strait-was used to determine the full water column structure of the cyclones. On …
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Influences of the Darrieus-Landau instability on premixed turbulent flames
… resulting from two-dimensional unsteady flame-vortex interactions, which can be thought as simplifications of three-dimensional problems. Furthermore, probability distribution functions of flame surface curvature, strain and mean flame position show that the presence of the Darrieus-Landau …
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2D PIV Study of Grid Turbulence
… the predominance of enstrophy amplification by vortex stretching. The observations were validated when compared with $2D$ slices of $3D$ data from a direct numerical simulation of isotropic flow. Finally, a study of homogenisation was carried out by mapping an area of $14M\times 4M$ in the down- …
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An experimental study of a turbulent wing-body junction and wake flow
… clearly show the characteristic horseshoe vortex flow structure. The vortex flow structure is elliptically shaped, with â (W)/â Y forming the primary component of streamwise vorticity. Near wall measurements show a thin layer of highly concentrated vorticity, underneath and opposite in sign …
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Observations of misovortices within the 7 January 2014 Long Lake-Axis-Parallel lake-effect snow band during the Ontario Winter Lake-effect Systems Project
… instability (HSI) was the main mechanism for misovortexgenesis in two LLAP bands analyzed during the LLAP Project. With data from only a single mobile Doppler radar available, however, this hypothesis was not testable. In the present study, three-dimensional dual-Doppler (DD) wind syntheses reveal …
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Numerical lnvestigation of Disturbance Environments in Low Pressure Turbines
… flat plate subjected to a convecting free-stream vortex of fixed strength and at a fixed height over the plate. The first configuration represents the ‘ultra high-lift’ blades for the next generation low pressure turbine. The local pressure gradient induced by the convecting vortex in the second …
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The dynamics of mean circulation on the continental shelf
… balance vorticity between bottom stress curl and vortex stretching. The near-bottom flow field is studied both analytically and numerically under forcing by wind, deep ocean flow, and long-isobath density differences. Model solutions are derived for circulations over a shelf/slope topography …
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On subannual variability in the abyssal ocean
… increase in seawater density. Vortex stretching is the primary source of cyclonic vorticity, while vortex tilting is a non-negligible sink. The deep pressure tendency, vorticity fluxes, and ageostrophic flows are diagnosed, and their similarities and differences with …
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On Subannual Variability in the Abyssal Ocean
… increase in seawater density. Vortex stretching is the primary source of cyclonic vorticity, while vortex tilting is a non-negligible sink. The deep pressure tendency, vorticity fluxes, and ageostrophic flows are diagnosed, and their similarities and differences with …
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