Even- and odd-parity finite-element transport solutions in the thick diffusion limit

Conference · Mon Jan 07 04:00:00 EST 1991

OSTI ID:6042904

Adams, M L

We analyze the behavior of odd-parity continuous finite-element methods (CFEMs) for problems that contain diffusive regions. We find that each of these method produces a solution that, to leading order inside diffusive regions, satisfies a discretization of the diffusion equation. We find further that these leading-order solutions satisfy boundary conditions that can lead to large errors in the interior solution. We recognize, however, that we can combine an odd-purity CFEM solution and an even-parity CFEM solution and obtain a solution that satisfies very accurate boundary conditions. Our analysis holds in three-dimensional Cartesian geometry, with an arbitrary spatial grid. We give numerical results from slab-geometry; these invariably agree with the predictions of the analysis. Finally, we introduce a rapidly-convergent diffusion-synthetic acceleration scheme for the odd-parity CFEMs, which we believe is new. 18 refs., 3 figs.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6042904
• Report Number(s): UCRL-JC-104788; CONF-910414--18; ON: DE91007618
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ASYMPTOTIC SOLUTIONS
BOUNDARY CONDITIONS
DIFFUSION
ELECTROMAGNETIC RADIATION
FINITE ELEMENT METHOD
FUNCTIONS
NUMERICAL SOLUTION
RADIATION TRANSPORT
RADIATIONS
THERMAL RADIATION
WAVE FUNCTIONS