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Incorporating Electrokinetic Phenomena into EBNavierStokes

Description: Motivated by the recent interest in using electrokinetic effects within microfluidic devices, they have extended the EBNavierStokes code to be able to handle electrokinetic effects. With this added functionality, the code becomes more useful for understanding and designing microfluidic devices that take advantage of electrokinetic effects (e.g. pumping and mixing). Supporting the simulation of electrokinetic effects required three main extensions to the existing code: (1) addition of an electric field solver, (2) development of a module for accurately computing the Smulochowski slip-velocity at fluid-solid boundaries, and (3) extension of the fluid solver to handle nonuniform inhomogeneous Dirichlet boundary conditions. The first and second extensions were needed to compute the electrokinetically generated slip-velocity at fluid-solid boundaries. The third extension made it possible for the fluid flow to be driven by a slip-velocity boundary condition (rather than by a pressure difference between inflow and outflow). In addition, several small changes were made throughout the code to make it compatible with these extensions. This report documents the changes to the EBNavierStokes code required to support the simulation of electrokinetic effects. They begin with a brief overview of the problem of electrokinetically driven flow. Next, they present a detailed description of the changes to the EBNavierStokes code. Finally, they present some preliminary results and discuss future directions and improvements to the code.
Date: January 10, 2006
Creator: Chu, K & Trebotich, D
Partner: UNT Libraries Government Documents Department

Pulsar Electrodynamics: a Time-dependent View

Description: Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developments in force-free modeling of the magnetospheric structure. In particular, we discuss a new method for solving the equations of time-dependent force-free relativistic MHD in application to pulsars. This method allows to dynamically study the formation of the magnetosphere and its response to perturbations, opening a qualitatively new window on pulsar phenomena. Applications of the method to other magnetized rotators, such as magnetars and accretion disks, are also discussed.
Date: April 10, 2006
Creator: Spitkovsky, Anatoly
Partner: UNT Libraries Government Documents Department

Spectroscopy at the high-energy electron beam ion trap (Super EBIT)

Description: The following progress report presents some of the x-ray measurements performed during the last year on the Livermore SuperEBIT facility. The measurements include: direct observation of the spontaneous emission of the hyperfine transition in ground state hydrogenlike holmium, {sup 165}Ho{sup 66{plus}}; measurements of the n {equals} 2 {r_arrow} 2 transition energies in neonlike thorium, Th{sup 80{plus}}, through lithiumlike thorium, Th{sup 87{plus}}, testing the predictions of quantum electrodynamical contributions in high-Z ions up to the 0.4{percent} level; measurements of the isotope shift of the n= 2 {r_arrow} 2 transition energies between lithiumlike through carbonize uranium, {sup 233}U{sup 89{plus}...86{plus}} and {sup 238}U{sup 89{plus}...86{plus}}, inferring the variation of the mean- square nuclear charge radius; and high-resolution measurements of the K{alpha} radiation of heliumlike xenon, Xe{sup 52 {plus}}, using a transmission-type crystal spectrometer, resolving for the first time the ls2p{sup 3}P{sub 1} {r_arrow} 1S{sup 2} {sup 1}S{sub 0} and ls2s{sup 3}S{sub 1} {r_arrow} 1S{sup 2} {sup 1}S{sub 0} transitions individually. 41 refs., 9 figs., 1 tab.
Date: July 10, 1996
Creator: Widmann, K.; Beiersdorfer, P. & Crespo Lopez-Urrutia, J.R.
Partner: UNT Libraries Government Documents Department