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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 21 for “"MHD simulations"”.
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Numerical MHD Simulations in Dynamical Spacetimes
… energetic events in the universe using computer simulations. These simulations must account for the relevant physical processes while, at the same time, evolving the spacetime according to Einstein's equations of general relativity. In particular, magnetohydrodynamics (MHD) and relativistic …
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Formation and stability of the solar tachocline in MHD simulations
… present work develops this idea with numerical simulations including additional effects like meridional circulation. It is shown that a relic field of 1~Gauss or smaller would be sufficient to explain the observed thickness of the tachocline. The stability of the solar tachocline is addressed as …
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Next Generation Algorithms for Magnetically Confined Fusion Reactor Simulations
… for whole-system nuclear fusion reactor simulations, with a focus on predicting and understanding non-linear MHD (magnetohydrodynamics) plasma instabilities and disruption events. The objective is to model all reactor regions (plasma, quasi-vacuum, and containment vessel) within a single …
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Verification and Validation of Magnetohydrodynamics Simulations of Electrically Exploded Conductors
… 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 validation. Verification …
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Effect of magnetic seed fields on Lyman Alpha emission from distant quasars
… Universe and magnified via magnetohydrodynamic (MHD) processes could cause perturbations in the thermodynamic state of the gas in the intergalactic medium which affect the Lyman-Alpha spectrum we observe. In this work we investigate to what extent the properties of the Lyman-Alpha forest are …
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High resolution spectroscopy of photospheric bright points
… with magnetic elements. Solar magneto-convection simulations indicate that the formationof these structures is accompanied with large downflows that can reach velocities of several km/s. In some cases, the downflowing gas may rebound in the deeper layers which can cause <br>an upward-propagating …
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Numerical simulations of mass outflows from star-forming regions
… two dimensional radiation magnetohydrodynamics (RMHD) code is described in detail. Well developed Eulerian hydrodynamic algorithms are used, but are implemented in a new covariant formalism which facilitates simulations in any orthogonal coordinate system. The recently developed constrained …
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High resolution spectropolarimetric diagnostics of weak, small-scale magnetic fields in the solar photosphere
… three-dimensional radiative magnetohydrodynamic (MHD) simulation is used with SIR to produce synthetic observables in the same spectral window as observed by the GRIS-IFU. A parallelized wrapper to SIR is then used to perform nearly 14 million inversions of the synthetic spectra to test how well …
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Particle acceleration at null-point current sheets in the solar corona
… and rearrange into a lower energy geometry. MHD simulations can be used to create analytical geometries of reconnecting fields within which particle acceleration can be simulated. A code was written to use a predictor-corrector algorithm to model the full motion of particles in such fields, …
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Extending the dielectric formalism in warm dense matter: collisions, dynamic structure factors, and stopping powers
… radiation- or magneto- hydrodynamics (R/MHD) codes. In turn, the accuracy of R/MHD simulations rely on detailed descriptions of the material properties like transport coefficients, stopping powers, scattering and absorption spectra, and many other quantities in the WDM regime. However, …
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Merging black hole binaries in gaseous environments: simulations in general-relativistic magnetohydrodynamics
… general relativistic, (magneto)hydrodynamic simulations of merging, equal-mass, nonspinning BHBH binaries embedded in gaseous environments. We evolve the metric using the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation with standard moving puncture gauge conditions and handle the …
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Shearing waves and the MRI dynamo in stratified accretion discs
… source of dissipative turbulence. Previous local simulations of the MRI have shown that the dynamo changes character on addition of vertical stratification. We investigate numerically 3D hydrodynamic shearing waves with a conserved Hermitian form in an isothermal disc with vertical gravity, and …
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Examining the growth and evolution of magnetic fields in clusters of galaxies: a numerical perspective
… large-scale cosmological magnetohydrodynamic (MHD) simulations of the formation of galaxy clusters including the seeding and growth of magnetic fields. Using large-scale cosmological simulations with the FLASH code combined with a simplified model of the acceleration of cosmic rays responsible …
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Simulations of active galactic nucleus feedback in the cores of galaxy clusters
… adaptive mesh refinement (AMR) hydrodynamics simulations of the cores of galaxy clusters. Modeling of feedback from AGN that consist of central super-massive black holes (SMBH) in galaxy clusters through simulations is a very challenging problem. Due to limited resolution to resolve physics at …
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Experimental Studies of Magnetic Field Generation and Saturation Mechanisms in Laser-Driven Plasmas
… are presented and previewed with FLASH MHD simulations. Connections of self-generated magnetic fields to inertial confinement fusion are made. Experiments using small-scale gas-filled hohlraums on OMEGA used to study both the hydrodynamic stability of the gas-ablation interface and …
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Evolution of 3-d magnetic topology in flare-productive active regions
… behind solar flares based on observations, simulations and nonlinear force-free (NLFF) field modeling of magnetic fields. The data used in this study are obtained from several ground-based or space-borne instruments, including BBSO/DVMG, Hinode/SOT/SP, SDO/HMI and GOES. In addition, the …
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Interstellar turbulence driven by magneto-rotational instability
… the help of 3D global magneto-hydrodynamical (MHD) simulations. The calculations were done with the time-stepping ZEUS 3D code using massive parallelization. The alpha-Omega dynamo is known to be one of the most efficient mechanisms to reproduce the observed global galactic fields. The presence …
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Box-Simulationen von rotierender Magnetokonvektion im flüssigen Erdkern
… flüssigen Erdkern Numerische Simulationen der 3D-MHD Gleichungen sind mit Hilfe des Codes NIRVANA durchgeführt worden. Die Gleichungen für kompressible rotierende Magnetokonvektion wurden für erdähnliche Bedingungen numerisch in einer kartesischen Box gelöst. Charakteristische Eigenschaften …
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Development of high energy pulsed plasma simulator for plasma-lithium trench experiment
… and a plasma heat flux of 0.42 GW/m2. Ideal MHD simulations are carried out to verify the experimental results on plasma transport. Ideal MHD and Athena MHD simulation code are found to be reasonable approximations to simulate behaviors of the plasma in the experimental condition. Simulation …
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Statistical properties of Radio Halos and the re-acceleration model
… in terms of the reacceleration scenario in which MHD turbulence injected during these cluster mergers re-accelerates high energy particles in the ICM. The physics involved in this scenario is very complex and model details are difficult to test, however this model clearly predicts some simple …
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