Initial performance of fully-coupled AMG and approximate block factorization preconditioners for solution of implicit FE resistive MHD.

Conference · Tue Jun 01 04:00:00 EDT 2010

OSTI ID:1020538

Shadid, John Nicolas; Lin, Paul Tinphone; Pawlowski, Roger Patrick; Chacon, Luis ^[1]; Cyr, Eric C; Tuminaro, Raymond Stephen

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1. Oak Ridge National Laboratory

This brief paper explores the development of scalable, nonlinear, fully-implicit solution methods for a stabilized unstructured finite element (FE) discretization of the 2D incompressible (reduced) resistive MHD system. The discussion considers the stabilized FE formulation in context of a fully-implicit time integration and direct-to-steady-state solution capability. The nonlinear solver strategy employs Newton-Krylov methods, which are preconditioned using fully-coupled algebraic multilevel (AMG) techniques and a new approximate block factorization (ABF) preconditioner. The intent of these preconditioners is to enable robust, scalable and efficient solution approaches for the large-scale sparse linear systems generated by the Newton linearization. We present results for the fully-coupled AMG preconditioner for two prototype problems, a low Lundquist number MHD Faraday conduction pump and moderately-high Lundquist number incompressible magnetic island coalescence problem. For the MHD pump results we explore the scaling of the fully-coupled AMG preconditioner for up to 4096 processors for problems with up to 64M unknowns on a CrayXT3/4. Using the island coalescence problem we explore the weak scaling of the AMG preconditioner and the influence of the Lundquist number on the iteration count. Finally we present some very recent results for the algorithmic scaling of the ABF preconditioner.

• Research Organization: Sandia National Laboratories
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1020538
• Report Number(s): SAND2010-3789C
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
COALESCENCE
COMPUTERIZED SIMULATION
FACTORIZATION
FLUID MECHANICS
MAGNETIC ISLANDS
PERFORMANCE