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Finite element analysis of volumetrically heated fluids in an axisymmetric enclosure

Description: A general purpose finite element computer code has been used to analyze the steady state and transient response of a confined fluid that is heated volumetrically. The numerical procedure is demonstrated to be capable of resolving flow fields of considerable complexity without undue computational expense. Results are discussed for a Grashof number range (4.0 x 10/sup 4/ to 4.0 x 10/sup 6/) in which the flow varies from a steady, single cell configuration to a multiple cell configuration that includes a periodic interaction.
Date: January 1, 1979
Creator: Gartling, D.K.
Partner: UNT Libraries Government Documents Department

Finite element analysis of thermal convection in deep ocean sediments

Description: Of obvious importance to the study and engineering of a seabed disposal is the determination of the temperature and fluid flow fields existing in the sediment layer and the perturbation of these fields due to the implantation of localized heat sources. The fluid mechanical and heat transfer process occurring in oceanic sediments may be characterized as free (or natural) convection in a porous material. In the case of an undisturbed sediment layer, the driving force for the natural circulation of pore water comes from the geothermal heat flux. Current theories for heat flow from the sea floor suggest the possibility of large scale hydrothermal circulation in the oceanic crust (see e.g., Ribando, et al. 1976) which is in turn coupled with a convection process in the overlying sediment layer (Anderson 1980, Anderson, et al. 1979). The introduction of a local heat source, such as a waste canister, into a saturated sediment layer would by itself initiate a convection process due to buoyancy forces. Since the mathematical description of natural convection in a porous medium is of sufficient complexity to preclude the use of most analytic methods of analysis, approximate numerical procedures are often employed. In the following sections, a particular type of numerical method is described that has proved useful in the solution of a variety of porous flow problems. However, rather than concentrate on the details of the numerical algorithm the main emphasis of the presentation will be on the types of problems and results that are encountered in the areas of oceanic heat flow and seabed waste disposal.
Date: January 1, 1980
Creator: Gartling, D. K.
Partner: UNT Libraries Government Documents Department

COYOTE: a finite-element computer program for nonlinear heat-conduction problems

Description: COYOTE is a finite element computer program designed for the solution of two-dimensional, nonlinear heat conduction problems. The theoretical and mathematical basis used to develop the code is described. Program capabilities and complete user instructions are presented. Several example problems are described in detail to demonstrate the use of the program.
Date: October 1, 1982
Creator: Gartling, D.K.
Partner: UNT Libraries Government Documents Department

COYOTE: a finite element computer program for nonlinear heat conduction problems

Description: COYOTE is a finite element computer program designed for the solution of two-dimensional, nonlinear heat conduction problems. The theoretical and mathematical basis used to develop the code is described. Program capabilities and complete user instructions are presented. Several example problems are described in detail to demonstrate the use of the program.
Date: June 1, 1978
Creator: Gartling, D.K.
Partner: UNT Libraries Government Documents Department

TORO II: A finite element computer program for nonlinear quasi-static problems in electromagnetics: Part 1, Theoretical background

Description: The theoretical and numerical background for the finite element computer program, TORO II, is presented in detail. TORO II is designed for the multi-dimensional analysis of nonlinear, electromagnetic field problems described by the quasi-static form of Maxwell`s equations. A general description of the boundary value problems treated by the program is presented. The finite element formulation and the associated numerical methods used in TORO II are also outlined. Instructions for the use of the code are documented in SAND96-0903; examples of problems analyzed with the code are also provided in the user`s manual. 24 refs., 8 figs.
Date: May 1, 1996
Creator: Gartling, D.K.
Partner: UNT Libraries Government Documents Department

TORO II: A finite element computer program for nonlinear quasi-static problems in electromagnetics: Part 2, User`s manual

Description: User instructions are given for the finite element, electromagnetics program, TORO II. The theoretical background and numerical methods used in the program are documented in SAND95-2472. The present document also describes a number of example problems that have been analyzed with the code and provides sample input files for typical simulations. 20 refs., 34 figs., 3 tabs.
Date: May 1, 1996
Creator: Gartling, D.K.
Partner: UNT Libraries Government Documents Department

Thermal/fluid modeling of the response of saturated marine red clays to emplacement of nuclear waste

Description: This report discusses the heat and mass transport in marine red clay sediments being considered as a nuclear waste isolation medium. Development of two computer codes, one to determine temperature and convective velocity fields, the other to analyze the nuclide migration problem, is discussed and preliminary results from the codes reviewed. The calculations indicate that for a maximum allowable sediment/canister temperature range of 200 to 250/sup 0/C, the sediment can absorb about 1.5 kW initial power from waste in a 3 m long by 0.3 m diameter canister. The resulting fluid displacement due to convection is found to be small, less than 1 m. The migration of four nuclides, /sup 239/Pu, /sup 137/Cs, /sup 129/I, and /sup 99/Tc were computed for a canister buried 30 m deep in 60 m thick sediment. It was found that the /sup 239/Pu and /sup 137/Cs, which migrate as cations and have relatively high distribution coefficients, are essentially completely contained in the sediment. The anionic species, /sup 129/I and /sup 99/Tc, which have relatively low distribution coefficients, broke through the sediment in about 5000 years. The resultant peak injection rates which occur at about 15,000 years were extremely small (0.5 ..mu..Ci/year for /sup 129/I and 180 ..mu..Ci/year for /sup 99/Tc).
Date: January 1, 1979
Creator: McVey, D.F.; Gartling, D.K. & Russo, A.J.
Partner: UNT Libraries Government Documents Department

CUERVO: A finite element computer program for nonlinear scalar transport problems

Description: CUERVO is a finite element code that is designed for the solution of multi-dimensional field problems described by a general nonlinear, advection-diffusion equation. The code is also applicable to field problems described by diffusion, Poisson or Laplace equations. The finite element formulation and the associated numerical methods used in CUERVO are outlined here; detailed instructions for use of the code are also presented. Example problems are provided to illustrate the use of the code.
Date: November 1995
Creator: Sirman, M. B. & Gartling, D. K.
Partner: UNT Libraries Government Documents Department

Computational and experimental methods for enclosed natural convection

Description: Two computational procedures and one optical experimental procedure for studying enclosed natural convection are described. The finite-difference and finite-element numerical methods are developed and several sample problems are solved. Results obtained from the two computational approaches are compared. A temperature-visualization scheme using laser holographic interferometry is described, and results from this experimental procedure are compared with results from both numerical methods.
Date: October 1, 1977
Creator: Larson, D.W.; Gartling, D.K. & Schimmel, W.P. Jr.
Partner: UNT Libraries Government Documents Department

Finite element model for heat conduction in jointed rock masses

Description: A computatonal procedure for simulating heat conduction in a fractured rock mass is proposed and illustrated in the present paper. The method makes use of a simple local model for conduction in the vicinity of a single open fracture. The distributions of fractures and fracture properties within the finite element model are based on a statistical representation of geologic field data. Fracture behavior is included in the finite element computation by locating local, discrete fractures at the element integration points.
Date: January 1, 1981
Creator: Gartling, D.K. & Thomas, R.K.
Partner: UNT Libraries Government Documents Department

Spectral decomposition in advection-diffusion analysis by finite element methods

Description: In a recent study of the convergence properties of finite element methods in nonlinear fluid mechanics, an indirect approach was taken. A two-dimensional example with a known exact solution was chosen as the vehicle for the study, and various mesh refinements were tested in an attempt to extract information on the effect of the local Reynolds number. However, more direct approaches are usually preferred. In this study one such direct approach is followed, based upon the spectral decomposition of the solution operator. Spectral decomposition is widely employed as a solution technique for linear structural dynamics problems and can be applied readily to linear, transient heat transfer analysis; in this case, the extension to nonlinear problems is of interest. It was shown previously that spectral techniques were applicable to stiff systems of rate equations, while recent studies of geometrically and materially nonlinear structural dynamics have demonstrated the increased information content of the numerical results. The use of spectral decomposition in nonlinear problems of heat and mass transfer would be expected to yield equally increased flow of information to the analyst, and this information could include a quantitative comparison of various solution strategies, meshes, and element hierarchies.
Date: August 11, 1978
Creator: Nickell, R.E.; Gartling, D.K. & Strang, G.
Partner: UNT Libraries Government Documents Department

TORO II simulations of induction heating in ferromagnetic materials

Description: TORO II is a finite element computer program that is used in the simulation of electric and magnetic fields. This code, which was developed at Sandia National Laboratories, has been coupled with a finite element thermal code, COYOTE II, to predict temperature profiles in inductively heated parts. The development of an effective technique to account for the nonlinear behavior of the magnetic permeability in ferromagnetic parts is one of the more difficult aspects of solving induction heating problems. In the TORO II code, nonlinear, spatially varying magnetic permeability is approximated by an effective permeability on an element-by-element basis that effectively provides the same energy deposition that is produced when the true permeability is used. This approximation has been found to give an accurate estimate of the volumetric heating distribution in the part, and predicted temperature distributions have been experimentally verified using a medium carbon steel and a 10kW industrial induction heating unit. Work on the model was funded through a Cooperative Research and Development Agreement (CRADA) between the Department of Energy and General Motors` Delphi Saginaw Steering Systems.
Date: September 1, 1997
Creator: Adkins, D.R.; Gartling, D.K.; Kelley, J.B. & Kahle, P.M.
Partner: UNT Libraries Government Documents Department

Analysis of heat and mass transfer in sub-seabed disposal of nuclear waste

Description: A mathematical basis is developed for the prediction of thermal and radionuclide transport in marine sediments. The theory is applied to the study of radioactive waste disposal by emplacement, in specially designed containers, well below the sediment/water interface. Numerical results are obtained for a specified model problem through use of two computer programs designed primarily for the analysis of waste disposal problems. One program (MARIAH) provides descriptions of the temperature and velocity fields induced by the presence of a container of thermally active nuclear waste. A second program (IONMIG), which utilizes the results of the thermal analysis, is used to provide predictions for the migration of four representative radionuclides: /sup 239/Pu, /sup 137/Cs, /sup 129/I, and /sup 99/Tc.
Date: January 1, 1980
Creator: Hickox, C. E.; Gartling, D. K.; McVey, D. F.; Russo, A. J. & Nuttall, H. E.
Partner: UNT Libraries Government Documents Department

Finite-element analysis of an epoxy-curing process

Description: A finite element numerical procedure is used to study the curing of an epoxy compound. The problem involves the gelation of an incompressible liquid due to an exothermic chemical reaction. Nonuniform temperature fields produce buoyancy-driven fluid motions that interact with the solidifying material. The numerical simulations provide temperature histories and the progression of the gel front that are compared with experimental data.
Date: January 1, 1983
Creator: Gartling, D K; Hickox, C E & Nunziato, J W
Partner: UNT Libraries Government Documents Department

Multidimensional thermal-chemical cookoff modeling

Description: Multidimensional thermal/chemical modeling is an essential step in the development of a predictive capability for cookoff of energetic materials in systems subjected to abnormal thermal environments. COYOTE II is a state-of-the-art two- and three-dimensional finite element code for the solution of heat conduction problems including surface-to-surface thermal radiation heat transfer and decomposition chemistry. Multistep finite rate chemistry is incorporated into COYOTE II using an operator-splitting methodology; rate equations are solved element-by-element with a modified matrix-free stiff solver, CHEMEQ. COYOTE II is purposely designed with a user-oriented input structure compatible with the database, the pre-processing mesh generation, and the post-processing tools for data visualization shared with other engineering analysis codes available at Sandia National Laboratories. As demonstrated in a companion paper, decomposition during cookoff in a confined or semi-confined system leads to significant mechanical behavior. Although mechanical effect are not presently considered in COYOTE II, the formalism for including mechanics in multidimensions is under development.
Date: August 1, 1994
Creator: Baer, M. R.; Gross, R. J.; Gartling, D. K. & Hobbs, M. L.
Partner: UNT Libraries Government Documents Department