A simplified angular multigrid method to accelerate S{sub N} calculations

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Transactions of the American Nuclear Society

OSTI ID:20005775

Kucukboyaci, V; Haghighat, A

In problems with optically thick regions and high scattering ratios (c {minus} ratio = {sigma}{sub s}/{sigma}{sub t}), particles that are making a large number of scattering collisions in a single energy group contribute significantly to scalar flux distribution; consequently, the convergence of the source iteration (SI) method can become very slow. For certain cross-section libraries, groups in the thermal energy range may be very broad, and particles may undergo many scattering events before being removed from the group. One remedy to fix the slow convergence is to narrow the energy group ranges; however, this means that the transport equation must be solved for more groups, which may lead to further computational inefficiency. Hence, numerous techniques have been devised to accelerate the SI method, such as rebalance, diffusion synthetic acceleration (DSA), and multigrid acceleration schemes. Multigrid acceleration is a general type of acceleration method, which has been applied to transport calculations by using it directly for the S{sub N} equations and/or for the DSA equations. The basic principle of the multigrid method is to use a sequence of coarse and fine grids to obtain an accelerated solution on the fine grid. Here, the authors briefly explain the general idea of the multigrid method.

• Research Organization: Pennsylvania State Univ., University Park, PA (US)
• OSTI ID: 20005775
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 81; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CONVERGENCE
DISCRETE ORDINATE METHOD
ITERATIVE METHODS
MESH GENERATION
TRANSPORT THEORY