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in subjects: "Boundary Conditions"

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SPXCPL: two-dimensional modeling program of self-potential effects from cross-coupled fluid and heat flow (User's Guide and documentation for Version 1. 0)

The program is applicable to the calculation of self-potential effects due to fluid flow (electrokinetic effects) and heat flow (thermoelectric effects). The geological structure is two dimensional but the sources can be either finite line sources or point sources. The accuracy of the calculated potentials depends on the model discretization and the distance from the source(s). For the default mesh, the accuracy is usually a few percent at a distance of about one unit from the source. Surface b… more

Date: March 1, 1982

Creator: Sill, W. R. & Killpack, T. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Non-linear numerical studies of the tearing mode

A non-linear, time dependent, hydromagnetic model is developed and applied to the tearing mode, one of a class of instabilities which can occur in a magnetically confined plasma when the constraint of infinite conductivity is relaxed. The model is based on the eight partial differential equations of resistive magnetohydrodynamics (MHD). The equations are expressed as a set of conservation laws which conserves magnetic flux, momentum, mass, and total energy. These equations are then written in g… more

Date: January 1, 1978

Creator: Schnack, D.D. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Magnetic fusion with high energy self-colliding ion beams

Field-reversed configurations of energetic large orbit ions with neutralizing electrons have been proposed as the basis of a fusion reactor. Vlasov equilibria consisting of a ring or an annulus have been investigated. A stability analysis has been carried out for a long thin layer of energetic ions in a low density background plasma. There is a growing body of experimental evidence from tokamaks that energetic ions slow down and diffuse in accordance with classical theory in the presence of lar… more

Date: June 1, 1992

Creator: Rostoker, N.; Wessel, F. (California Univ., Irvine, CA (United States)); Maglich, B. (Advanced Physics Corp., Irvine, CA (United States)) & Fisher, A. (Naval Research Lab., Washington, DC (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Study of ICRF wave propagation and plasma coupling efficiency in a linear magnetic mirror device

Ion Cyclotron Range of Frequency (ICRF) wave propagation in an inhomogeneous axial magnetic field in a cylindrical plasma-vacuum system has historically been inadequately modelled. Previous works either sacrifice the cylindrical geometry in favor of a simpler slab geometry, concentrate on the resonance region, use a single mode to represent the entire field structure, or examine only radial propagation. This thesis performs both analytical and computational studies to model the ICRF wave-plasma… more

Date: July 1, 1991

Creator: Peng, S.Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Optimal Linfinity estimates for some Galerkin methods for the Dirichlet problem

Optimal L/sup infinity/ error estimates are established for a few different finite-element-type methods for the Dirichlet problem in a bounded domain. The methods are selected so as to avoid the necessity of imposing boundary conditions on the trial functions, usually difficult in practice. Three specific methods are treated. These are the method of interpolated boundary conditions and two methods of Nitsche. The trial spaces, S/sup h/, consist of continuous piecewise polynomials of degree less… more

Date: August 1, 1977

Creator: Goldstein, C I & Scott, R

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Prediction of the migration of several radionuclides in ocean sediment with the computer code IONMIG: a preliminary report

A computer code, IONMIG, which is used to calculate the far-field transport of radionuclides through ocean sediment by diffusion and convection is described. The code uses a two-dimensional, axisymmetric, explicit finite difference formulation. Preliminary results for several species (Cs, Pu, I, Tc) are given.

Date: May 1, 1980

Creator: Russo, A.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Thermally Induced Structural Changes in Coal Combustion

The effect of particle shape on char burnout is investigated in the limit of shrinking core combustion. As a first step, the particle temperature is assumed to proceed in the shrinking core regime and under conditions of negligible Stefan flow. The problem then reduces to calculating the oxygen concentration field around a non-spherical particle with the oxidation reaction taking place on the external surface. This problem has been addressed by an analytical technique and a numerical technique.… more

Date: January 17, 1990

Creator: Gavalas, G. R. & Flagan, R. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

HEATING 7. 1 user's manual

HEATING is a FORTRAN program designed to solve steady-state and/or transient heat conduction problems in one-, two-, or three- dimensional Cartesian, cylindrical, or spherical coordinates. A model may include multiple materials, and the thermal conductivity, density, and specific heat of each material may be both time- and temperature-dependent. The thermal conductivity may be anisotropic. Materials may undergo change of phase. Thermal properties of materials may be input or may be extracted fr… more

Date: July 1, 1991

Creator: Childs, K.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

FLOWTRAN-TF code description

FLOWTRAN-TF is a two-component (air-water), two-phase thermal-hydraulics code designed for performing accident analyses of SRS reactor fuel assemblies during the Emergency Cooling System (ECS) phase of a Double Ended Guillotine Break (DEGB) Loss of Coolant Accident (LOCA). This report provides a brief description of the physical models in the version of FLOWTRAN-TF used to compute the Recommended K-Reactor Restart ECS Power Limit. This document is viewed as an interim report and should ultimate… more

Date: December 1, 1990

Creator: Flach, G.P. (ed.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Statistical theory of field fluctuations in a reversed-field pinch

A statistical description of three-dimensional, incompressible turbulence in an ideal, current-bearing, bounded magnetofluid is given both analytically and numerically. Our results are then compared with existing data taken from reversed-field pinch experiments.

Date: January 1, 1982

Creator: Turner, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Self-consistent calculations of edge temperature and self-sputtering of the limiter surface for tokamak fusion reactors

Self-sputtering and edge temperature estimates have been made for a tokamak fusion reactor with a normal incidence boundary using models for the power balance, plasma sheath, charge state, and sputtering coefficients. Both structural materials and low-Z coatings have been examined. From the self-sputtering standpoint, some materials will work only at very low edge temperatures; these will require a high recycling rate and a high radiation fraction.

Date: May 1, 1980

Creator: Brooks, J. N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Incorporation of boundary condition into the program POISSON

Two dimensional Cartesian and axially-symmetric problems in electrostatics or magnetostatics frequently are solved numerically by means of relaxation techniques - employing, for example, the program POISSON. In many such problems the ''sources'' (charges or currents, and regions of permeable material) lie exclusively within a finite closed boundary curve and the relaxation process in principle then could be confined to the region interior to such a boundary - provided a suitable boundary condit… more

Date: August 1, 1985

Creator: Caspi, S.; Helm, M. & Laslett, L.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

PATRAN and P/THERMAL Applications for Thermal Modeling. [SP-100 Ground Engineering Station]

The standard that has been established over the last decade or so in performing numerical modeling for analysis purposes is to make creation of the computational grid and results presentation less time and effort consuming than the analysis function itself. Software packages known as pre- and post-processors have been developed and made available in various forms and sizes for the engineering analyst's use. These packages reduce the effort and time required of the analyst to perform pre- and po… more

Date: July 1, 1991

Creator: Valdiviez, R. & Crea, B. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Progress in LTE and non-LTE transport calculations

The physical processes in ionized gases are reviewed along with recent calculations of particular processes. Ongoing opacity calculations at Los Alamos are described. Some of the open issues in the calculation of physical processes relevant to opacities are discussed. 39 refs., 7 figs.

Date: January 1, 1989

Creator: Keady, J.J.; Huebner, W.F.; Abdallah, J. Jr.; Magee, N.H. Jr. (Los Alamos National Lab., NM (USA); Southwest Research Inst., San Antonio, TX (USA) & Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Unit cell simulation for cylinders on a triangular pitch

In this paper we analyze the use of these equivalent unit cells for two problem-types of interest: a infinite lattice of small-diameter fuel pins and an infinite array of large shipping containers. Both void and water are considered as interstitial materials between the cylindrical units. The fuel pins modeled are uranium nitride pins clad with tantalum and niobium with a diameter of 1.1 cm. The pins are infinitely long. The shipping container model is a 55 gallon drum with 13 cm thick insulati… more

Date: January 1, 1991

Creator: O'Dell, R. D. & Schlesser, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast Algorithms for transport models

The first two years of this project were mainly focused on developing fast algorithms for the solution of the equations arising from models of single group isotropic transport of neutrally charged particles in slab geometry. In this context, the equation governing transport is an integral-differential equation involving one space variable and one angle variable. This paper discusses the solution of the equations.

Date: April 1992

Creator: Manteuffel, T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks

Electrostatic turbulence and transport measurements are performed on the Tokapole-II tokamak at the University of Wisconsin-Madison, as the safety-factor and the edge equilibrium gradients and varied substantially. Tokapole-II is a poloidal divertor tokamak capable of operating at a wide range of safety factors due to its unique magnetic limiter configuration. It also has retractable material limiters in a large scrape-off region, which permits the study of edge boundary conditions like density… more

Date: May 1, 1992

Creator: Tan, Ing Hwie.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Thermal effects of electrically conductive deposits in melter

The radioactive waste processed by the Defense Waste Processing Facility melter at the Savannah river Site contains noble metal fission-products. Operation of waste-glass melters treating commercial power reactor wastes indicates that accumulation of noble metals on melter floors can lead to distortion of electric heating patterns, loss of power, and possible electrode damage. Changes in melter geometry have been developed in Japan and Germany to minimize these effects. The two existing melters… more

Date: January 1, 1992

Creator: Choi, I.G.; Bickford, D.F. & Carter, J.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Methods for the solution of the two-dimensional radiation-transfer equation

We use the variable Eddington factor (VEF) approximation to solve the time-dependent two-dimensional radiation transfer equation. The transfer equation and its moments are derived for an inertial frame of reference in cylindrical geometry. Using the VEF tensor to close the moment equations, we manipulate them into a combined moment equation that results in an energy equation, which is automatically flux limited. There are two separable facets in this method of solution. First, given the variabl… more

Date: January 1, 1982

Creator: Weaver, R.; Mihalas, D. & Olson, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Carbon dioxide effects research and assessment program. Environmental and societal consequences of a possible CO/sub 2/-induced climate change: volume II, part I. Response of the West Antarctic ice sheet to CO/sub 2/-induced climatic warming

The paper proposes a research plan to deal with the question of what the response of the West Antarctic Ice Sheet would be to a rise in global temperatures caused by an anthropogenic CO/sub 2/ buildup in the atmosphere. The plan is designed to answer the following questions: (1) how fast is the ice mass changing now, and why; (2) how will the boundary conditions that affect the ice sheet respond to an atmospheric temperature change and how are those boundary conditions changing now; (3) what wi… more

Date: April 1, 1982

Creator: Bentley, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Incorporation of a circular boundary condition into the program POISSON

Two-dimensional problems in electrostatics or magnetostatics frequently are solved numerically by means of relaxation techniques. In many such problems the ''sources'' (charges or currents, and regions of permeable material) lie exclusively within a finite closed boundary curve and the relaxation process in principle then could be confined to the region interior to such a boundary - provided a suitable boundary condition is imposed onto the solution at that boundary. The present notes discuss a… more

Date: March 2, 1984

Creator: Caspi, S.; Helm, M. & Laslett, L.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Stanford Geothermal Program, reservoir and injection technology

This annual report of the Stanford Geothermal Program presents major projects in reservoir and injection technology. The four include: (1) an application of the boundary element method to front tracking and pressure transient testing; (2) determination of fracture aperture, a multi-tracer approach; (3) an analysis of tracer and thermal transients during reinjection; and, (4) pressure transient modeling of a non-uniformly fractured reservoir. (BN)

Date: December 1, 1988

Creator: Horne, R.; Ramey, H.J. Jr.; Miller, F.G.; Brigham, W.E. & Kruger, P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Improved numerical grid generation techniques for the B2 edge plasma code

Techniques used to generate grids for edge fluid codes such as B2 from numerically computed equilibria are discussed. Fully orthogonal, numerically derived grids closely resembling analytically prescribed meshes can be obtained. But, the details of the poloidal field can vary, yielding significantly different plasma parameters in the simulations. The magnitude of these differences is consistent with the predictions of an analytic model of the scrape-off layer. Both numerical and analytic grids … more

Date: June 1, 1992

Creator: Stotler, D. P. & Coster, D. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

ICRF heating in tokamaks

The current status of ICRF heating of Tokamak plasmas is described. Two aspects of the subject are discussed: the physics of wave damping and the evaluation of ion heating. Recent experiments in several Tokamak devices at the second harmonic of the deuteron cyclotron frequency have exhibited large discrepancies between the observed and predicted wave damping. A possible explanation, based upon enhanced cyclotron harmonic damping due to the proximity of the two-ion hybrid and cyclotron resonance… more

Date: October 1, 1977

Creator: Takahashi, H.

Item Type: Report

Partner: UNT Libraries Government Documents Department