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Showing 1 to 20 of 40 for “"Kelvin-Helmholtz Instability"”.
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Mesospheric Kelvin-Helmholtz instability
This work examines the Kelvin-Helmholtz instability, comparing features extracted from a numerical fully nonlinear model to radar and rocket measurements of free electron density and neutral motions in the mesosphere. Previous models of shear instability are reviewed, and relevant mesospheric …
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Kelvin-Helmholtz Instability in Magnetized Plasma
… in many systems in the universe, are generally Kelvin-Helmholtz unstable. If the medium is ionized, the presence of a magnetic field can influence the evolution of this instability; depending on its strength and orientation, the field has either a stabilizing or destabilizing effect. We …
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Kelvin-Helmholtz instability in aluminium reduction cells
… between the layers, which gives rise to a Kelvin-Helmholtz instability, and the study of this effect is the subject of the thesis. The role of the basic steady flow is focused in this analysis, while most previous MHD analyses neglect it and emphasise on the interaction between the …
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Multifluid Kelvin-Helmholtz instability in weakly ionised astrophysical plasmas
… on fluid instabilities, in particular the Kelvin-Helmholtz (KH) instability. The KH instability could, for example, play a role in the momentum transfer between the bowshock of a protostellar jet and its surrounding molecular cloud. In particular, changes to the development of the KH …
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Numerical analysis and visualization of the ionospheric Kelvin-Helmholtz instability
… irregularities; namely the evolution of the Kelvin-Helmholtz instability (KHI) is studied. The simulation model consists of two-dimensional, electrostatic, nonlinear, and time dependent fluid equations that describe the KHI evolution. Spectral and pseudospectral methods are used to solve the …
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MMS Observations of the Kelvin-Helmholtz Instability and Associated Ion Scale Waves
… must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various …
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The Numerical Simulation of Thunderstorm Outflow Dynamics (Gust Front, Kelvin-Helmholtz Instability, Wind Shear, Microbursts)
Two high-resolution, two-dimensional numerical models are developed and used to investigate the dynamics of thunderstorm outflows. The first model employs the set of unapproximated, inviscid, fully compressible hydrodynamical equations, while the second, more economical model is based on a …
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Numerical detection of complex singularities in two and three dimensions
… role in interfacial fluid dynamics such as Kelvin-Helmholtz instability, Rayleigh-Taylor instability, and Hele-Shaw flow. In this thesis, we present a new method for the numerical analysis of complex singularities in solutions to partial differential equations. In the method, we analyze the …
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Identifying Signatures of Plasma Waves and Reconnection Associated with Kelvin-Helmholtz Activity
… Recent work has shown that reconnection in Kelvin-Helmholtz vortices can transport plasma into the magnetosphere. Previous studies have also shown that mode conversion at the magnetopause can generate kinetic Alfvén wave (KAW) activity. Both magnetic reconnection and plasma wave activity can …
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Trace finite element method for material surface flows
… numerical examples which include simulation of Kelvin--Helmholtz instability at different Reynolds numbers on a sphere and torus, as well as tangential flow induced by inextensible radial deformations of a surface.
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Generalised nonlinear stability of stratified shear flows: adjoint-based optimisation, Koopman modes, and reduced models
… I considered that investigates the linear Taylor instability of layered stratified plane Couette flow, and show that the nonlinear evolution of the primary Taylor instability is not coupled to the form of the linearly unstable mode, in contrast to the Kelvin-Helmholtz instability, for example. I …
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Exploring global dynamics in a low order model of parallel shear flow
… has produced some famous instabilities e.g. Kelvin Helmholtz instability. An important, and as of yet mysterious, flow is Plane Couette flow in which turbulence is observable. Another observable phenomenon in Plane Couette flow is a “bursting” process whereby along with the linear laminar …
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CFD Analyses of Flow Structures in Air-Ingress and Rod Bundle Problems
… of PWRs. The objectives are to investigate the Kelvin-Helmholtz instability of the gravity-driven stratified flows inside a coaxial pipe and the effects caused by two types of spacers at the downstream of the rod bundle problem. Richardson extrapolation is used for the grid independent study. …
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Nonlinear effects on interfacial wave growth into slug flow
… velocity between the two fluids, two different instability mechanisms can create initial wave disturbances on the interface: the classic Kelvin-Helmholtz instability or shear induced instability. These instability mechanisms, which affect the initial growth of the disturbances on the interface, …
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Fully nonlinear interfacial waves in a bounded two-fluid system
… phase can be different, thus giving rise to the Kelvin-Helmholtz instability. Our objective is to study the competing effects of the Kelvin-Helmholtz instability coupled with a stably or unstably stratified fluid system (Rayleigh-Taylor instability) when surface tension is present to regularize …
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Mapping of the Quasi-periodic Oscillations at the Flank Magnetopause into the Ionosphere
… and four new cases believed to be caused by the Kelvin-Helmholtz Instability. Finally, we used auroral, magnetometer, and radar instruments to observe the ionospheric signatures. The ionospheric magnetic latitude determined using global MHD and Tsyganenko models ranged from 58.3-80.2 degrees in …
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Wall-Jet Turbulence and Mixing Control by Way of a Pulsed Inlet Velocity
… cyclic pulsing. The billow production by the Kelvin-Helmholtz instability, the instability that drives turbulence in a wall-jet, is modified by the excitation of the inlet velocity profile by a sine wave perturbation. Two types of wall-jet simulations are carried out, a two-dimensional …
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Understanding Vortex Reconnection in Complex Fluid Flows
… For higher values of $Re$ we observed a Kelvin-Helmholtz instability within the vortex sheets and the formation of additional vortex rings during the reconnection process.<br/><br/>We simulate a range of axial flow values to observe how kinetic helicity and twist evolve with reconnection. …
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Simulation of Multi-Layer-Liquid Sloshing Effects on Vessel Motions by Using Moving Particle Simulation
… waves at the interface were generated due to Kelvin-Helmholtz instability and the phenomenon was successfully reproduced by the developed MPS-simulation technique.
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Intense Shallow Magma Sediment Mingling within Dikes at Guffey Butte Maar, Idaho
… their differing densities mixing occurs through Kelvin-Helmholtz Instability. Mingling is separated into three categories: 1) Least Homogenized, 2) Moderate Homogenization, and 3) Homogenized. The different levels of mixing preserve the different stages of KelvinHelmholtz instability over a …
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