Development of a Discrete Ordinates Code System for Unstructured Meshes of Tetrahedral Cells, with Serial and Parallel Implementations

Abstract

A numerically stable, accurate, and robust form of the exponential characteristic (EC) method, used to solve the time-independent linearized Boltzmann Transport Equation, is derived using direct affine coordinate transformations on unstructured meshes of tetrahedra. This quadrature, as well as the linear characteristic (LC) spatial quadrature, is implemented in our transport code, called TETRAN. This code solves multi-group neutral particle transport problems with anisotropic scattering and was parallelized using High Performance Fortran and angular domain decomposition. A new, parallel algorithm for updating the scattering source is introduced. The EC source and inflow flux coefficients are efficiently evaluated using Broyden's rootsolver, started with special approximations developed here. TETRAN showed robustness, stability and accuracy on a variety of challenging test problems. Parallel speed-up was observed as the number of processors was increased using an IBM SP computer system.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1998
Accession Number
ADA358704

Entities

People

  • Rodney L. Miller

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Air Platforms
  • Counter WMD
  • Energy and Power Technologies
  • Space

DTIC Thesaurus Topics

  • Accuracy
  • Algorithms
  • Boltzmann Equation
  • Computational Fluid Dynamics
  • Computational Science
  • Computations
  • Computer Programming
  • Computers
  • Geometric Forms
  • Geometry
  • High Performance Computing
  • Mathematics
  • Numerical Analysis
  • Radiative Transfer
  • Scattering
  • Three Dimensional
  • Two Dimensional

Fields of Study

  • Physics

Readers

  • Electrical Engineering
  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)
  • Parallel and Distributed Computing.