Publications

Results 51–70 of 70
Skip to search filters

Correlations and Cascades in Magnetized Turbulence

IEEE Transactions on Plasma Science

Beckwith, Kristian B.; Grete, Philipp; O'Shea, Brian W.

Many terrestrial and astrophysical plasmas encompass very large dynamical ranges in space and time, which are not accessible by direct numerical simulations. Thus, idealized subvolumes are often used to study small-scale effects including the dynamics of magnetized turbulence. A significant aspect of magnetized turbulence is the transfer of energy from large to small scales, in part through the operation of a turbulent cascade. In this paper, we present a new shell-to-shell energy transfer analysis framework for understanding energy transfer within magnetized turbulence and in particular, through the cascade. We demonstrate the viability of this framework through application to a series of isothermal subsonic and supersonic simulations of compressible magnetized turbulence and utilize results from this analysis to establish a nonlinear benchmark for compressible magnetized turbulence in the subsonic regime. We further study how the autocorrelation time of the driving and its normalization systematically change properties of compressible magnetized turbulence. For example, we find that δ -in-time forcing with a constant energy injection leads to a steeper slope in kinetic energy spectrum and less efficient small-scale dynamo action. We examine how these results can impact a range of diagnostics relevant for a range of terrestrial and astrophysical applications.

More Details

Computational study of Fermi kinetics transport applied to large-signal RF device simulations

Journal of Computational Electronics

Miller, Nicholas C.; Grupen, Matt; Beckwith, Kristian B.; Smithe, David; Albrecht, John D.

A detailed description and analysis of the Fermi kinetics transport (FKT) equations for simulating charge transport in semiconductor devices is presented. The fully coupled nonlinear discrete FKT equations are elaborated, as well as solution methods and work-flow for the simulation of RF electronic devices under large-signal conditions. The importance of full-wave electromagnetics is discussed in the context of high-speed device simulation, and the meshing requirements to integrate the full-wave solver with the transport equations are given in detail. The method includes full semiconductor band structure effects to capture the scattering details for the Boltzmann transport equation. The method is applied to high-speed gallium nitride devices. Finally, numerical convergence and stability examples provide insight into the mesh convergence behavior of the deterministic solver.

More Details

Development of the Flexo XMHD Code

Beckwith, Kristian B.; Beckwith, Kristian B.; Beckwith, Kristian B.; Beckwith, Kristian B.; Bond, Stephen D.; Bond, Stephen D.; Bond, Stephen D.; Bond, Stephen D.; Granzow, Brian N.; Granzow, Brian N.; Granzow, Brian N.; Granzow, Brian N.; Jennings, Christopher A.; Jennings, Christopher A.; Jennings, Christopher A.; Jennings, Christopher A.; Martin, Matthew; Martin, Matthew; Martin, Matthew; Martin, Matthew; Porwitzky, Andrew J.; Porwitzky, Andrew J.; Porwitzky, Andrew J.; Porwitzky, Andrew J.; Stagg, Alan K.; Stagg, Alan K.; Stagg, Alan K.; Stagg, Alan K.; Voth, Thomas E.; Voth, Thomas E.; Voth, Thomas E.; Voth, Thomas E.

Abstract not provided.

Beyond the Fluid Approximation: Improved Modeling of the Intracluster Plasma

O'Shea, Brian W.; CHRISTLIEB, ANDREW C.; Beckwith, Kristian B.

This is the progress report for the grant "Beyond the Fluid Approximation: Improved Modeling of the Intracluster Plasma." We have made progress along several fronts, including code development and science. One paper has been published, and a second has been submitted and is about to be accepted. These are described below.

More Details
Results 51–70 of 70
Results 51–70 of 70