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Showing 1 to 20 of 39 for “"Magnetohydrodynamics (MHD)"”.
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Efficient High Order Ensemble for Fluid Flow
… algorithms for solving the full and reduced Magnetohydrodynamics (MHD) equations. The proposed ensemble methods require solving only one linear system with multiple right-hand sides for different realizations, reducing computational cost and simulation time. Four algorithms utilize a …
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Numerical MHD Simulations in Dynamical Spacetimes
… equations of general relativity. In particular, magnetohydrodynamics (MHD) and relativistic gravity are of crucial importance in astrophysical phenomena such as stellar collapse to black holes, binary neutron star mergers, supernovae, and gamma-ray bursts. Many of these phenomena are promising …
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Magnetohydrodynamic Simulations of Fast Instability Development in Pulsed-Power--Driven Explosions and Implosions of Electrical Conductors
… have suffered from magnetohydrodynamic (MHD) instabilities that lead to degradations in fusion yield. High levels of azimuthally-correlated MHD instability structures have been observed on cylindrical liner experiments without a pre-imposed axial magnetic field (Bz=0) elsewhere in the …
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Multifluid Kelvin-Helmholtz instability in weakly ionised astrophysical plasmas
By expanding on the principles of ideal magnetohydrodynamics (MHD), we examine the dynamics of weakly ionised astrophysical plasma flows in a multifluid regime. This numerical study is carried out using the multifluid MHD code HYDRA. An outline of the structure of this code is given in chapter 2 …
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The influence of Hall currents, plasma viscosity and electron inertia on magnetic reconnection solutions
… techniques within the theoretical frame work of magnetohydrodynamics (MHD). In Chapter 4 we use a line-tied X-point collapse model for compressible plasmas to investigate the role of viscosity on the energy release mechanism. This model also provides the basis for the investigation of Chapter 5 …
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A study of MHD and Monte Carlo simulations of high-current plasma beams in industrial applications
… high-current plasma beams are simulated using Magnetohydrodynamics (MHD), Monte Carlo (MC), and Integrated Hybrid MHD and MC (IMHDMC) methods. For the new MHD method, the pressure, velocity and density of the high-current plasma beams are obtained by solving the mass, energy and momentum …
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Verification and Validation of Magnetohydrodynamics Simulations of Electrically Exploded Conductors
… pulses through an initially solid conductor. Magnetohydrodynamics (MHD) simulations are used to interpret results of these pulsed power systems and design targets for future experiments. Formal testing of the numerical codes is necessary and broken into two categories: verification and …
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Unsteady newtonian and non-newtonian fluid flows in the circular tube in the presence of magnetic field using caputo-fabrizio derivative
This thesis investigates analytically the magnetohydrodynamics (MHD) transport of Newtonian and non-Newtonian fluids flows inside a circular channel. The flow was subjected to an external electric field for the Newtonian model and a uniform transverse magnetic field for all models. Pressure …
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Structure-preserving finite element and finite volume methods for nonlinear and time-dependent PDEs
… ranging from compressible fluid dynamics to magnetohydrodynamics (MHD) in tokamak geometries for nuclear fusion research. We begin by introducing a rotational formulation of the Stokes problem with Navier’s slip boundary conditions, followed by the development of an asymptotic-preserving and …
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Efficient finite-volume schemes for magnetohydrodynamic simulations in solar physics
… for solving the equations of (compressible) magnetohydrodynamics (MHD) in one, two, and three spatial dimensions. We introduce a new approximate Riemann solver for the ideal gas MHD equations (MHD-HLLEM) that outperforms all other solvers considered. We present and compare several Riemann …
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A Dynamic Coupled Magnetosphere-Ionosphere-Ring Current Model
… consists of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamics (MHD) simulation, the MIX ionosphere solver and the Rice Convection Model (RCM). We report some results of the coupled model using idealized inputs and model parameters. The algorithmic and physical components of the model are …
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Some aspects of magnetohydrodynamics
… the study of which is usually known as Magnetohydrodynamics (MHD), occur on a galactic, planetary or laboratory length scale; however in this thesis we concentrate on those phenomena which can be reproduced in the laboratory. In chapter 2 we study the laminar flow of uniformly …
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Catastrophe Model for the Onset of Fast Magnetic Reconnection
… (Sweet-Parker) reconnection, based on resistive magnetohydrodynamics (MHD), is a successful physical model but is far too slow to explain observed energy release rates. In collisionless (Hall) reconnection, dispersive waves introduced by the Hall effect lead to energy release rates fast enough to …
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Exploring the Variability of Accretion Discs with Stochastic Models
… constant viscosity models and those with full 3D magnetohydrodynamics (MHD), allowing for discs with realistic variability to be simulated with much less computational expensive. To explore the theory of propagating fluctuations in 2D, I then use this new model to run a series of simulations with …
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Unstructured Nodal Discontinuous Galerkin Method for Convection-Diffusion Equations Applied to Neutral Fluids and Plasmas
… equations, and plasma models, such as ideal-magnetohydrodynamics (MHD) and two-fluid plasma equations, are studied and benchmarked with various applications using this DG framework. Numerical computations of Rayleigh-Taylor instability growth with experimentally relevant parameters are …
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Magnetic Field Evolution in Black Hole Accretion Disks and Relativistic Jets
… to tackle both topics using three-dimensional magnetohydrodynamics (MHD) and relativistic magnetohydrodynamics (RMHD) simulations. In the first half (Chapters 2 and 3), I focus on the role of magnetic fields in simulations of thick accretion disks. At stake is a core question within the field …
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LONG TIME BEHAVIOR OF LINEAR AND NONLINEAR WAVES:LARGE LARGE AMPLITUDE TRAVELING QUASI-PERIODIC SOLUTIONS IN FLUID MECHANICS AND DYNAMICS OF LINEAR WAVE EQUATIONS
… models on $\mathbb{T}^2$: the non-resistive Magnetohydrodynamics (MHD) system and the 2D-Euler equation for rotating fluids ($\beta$-plane equation), both in presence of a large amplitude traveling wave external force with large velocity speed $\lambda \omega$, where $\lambda \gg 1$ is a …
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A Meshless Method for Magnetohydrodynamics and Applications to Protoplanetary Disks
… algorithm for simulating the equations of ideal magnetohydrodynamics and other systems of differential equations on an unstructured set of points represented by sample particles. Local, third-order, least-squares, polynomial interpolations (Moving Least Squares interpolations) are calculated from …
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General-relativistic magnetohydrodynamics simulations of black hole accretion disks: dynamics and radiative properties
… simulations, specifically general relativistic magnetohydrodynamics (GRMHD), to construct a realistic dynamical and radiation model of accretion disks. Our simulations are for black holes in low luminous regimes that probably possesses a hot and thick accretion disk. Flows in this regime are …
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