COYOTE : a finite element computer program for nonlinear heat conduction problems. Part I, theoretical background.

Abstract

The theoretical and numerical background for the finite element computer program, COYOTE, is presented in detail. COYOTE is designed for the multi-dimensional analysis of nonlinear heat conduction problems. 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 COYOTE are also outlined. Instructions for use of the code are documented in SAND2010-0714. iii iii PrefaceAt the time of release of the first version of COYOTE in mid-1978, it was not anticipated that the code would receive the usage and longevity that it currently enjoys. In response to user needs, the original program under went several minor upgrades plus a major revision during the late 1980's. In addition, a preliminary three-dimensional version of COYOTE was developed though it was not formally documented. Continued requests for additional capabilities combined with the significant changes in computer hardware and improved numerical algorithms, dictated the need for completely new versions of the older codes. In rewriting the COYOTE program, the two and three-dimensional codes were combined into a single software package, COYOTE II, that was released in 1994. The present series of reports describe the latest version (Version 5.0) of the program package, which has reverted to its original name, COYOTE, to avoid confusion in future releases.In an effort to make the program more flexible and more generally applicable, a number of new capabilities and features have been added to COYOTE to produce COYOTE, Version 5.0. The major extension of the code is the capability to optionally include one or two additional diffusion equations that may be coupled to the primary heat conduction equation. The variables in these added equations are available to the boundary conditions, source terms and material property functions in the conduction equation. Conversely, the temperature field is available to the auxiliary diffusion equations. As part of this expansion, a time harmonic option for heat transfer was also added. Two thermal diffusion equations are solved in this case for the real and imaginary parts of the temperature field. Some changes to the sequential solution algorithm for coupled conduction and radiation have been made to improve convergence of this type of method. A fully coupled conduction/radiation solution method has been generalized and reinstalled to allow operation in a parallel environment. The fully coupled algorithm was made possible by a complete changeover to the use of the Finite Element Interface (FEI) with the improved access to the solver libraries available in the Trilinos package. The code may now be compiled using either a single or double precision word length. Some minor changes in problem capability and control have also been added. Most notable among these changes are the allowance of a time evolving mass flow to a bulk node (due to chemical reaction) and user defined material parameters now being passed to user s...

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