Center for Extended MHD Modeling (PI: S. Jardin, PPPL) –Two extensively developed fully 3-D nonlinear MHD codes, NIMROD and M3D formed the basis for further advancement Center for Magnetic Reconnection Studies (PI: A. Bhattacharjee, U. of Iowa) –Interdisciplinary group drawn from applied mathematics, astrophysics,computer science, fluid dynamics, plasma physics, and space science communities EXTENDED MAGNETOHYDRODYNAMIC (MHD) SIMULATIONS

ADVANCED COMPUTING GOALS FOR MAGNETOHYDRODYNAMIC MODELING To advance parallel,scalable code development building on the strengths of existing fully nonlinear fluid codes To elucidate computationally efficient extensions of the appropriate fluid models to kinetic regime To implement specialized algorithms and simulation components to improve efficiency in collaboration with ISICS centers To develop advanced visualization techniques and database management for efficient display and analysis in collaboration with Fusion Collaboratory

CLOSE INTERACTIONS WITH APPLIED MATH CENTERS TOPS Center (ODU) –Direct comparison between PETSc and HYPRE routines for solving sparse linear systems –Comparing Algebraic Multigrid (AMG) from HYPRE, Incomplete LU (ILU) from HYPRE, Additive Schwartz (ASM) from PETSc –Additional discussions on restructuring, investigating non-linear solvers (Newton-Kyrlov) Sandia Linear Solvers group (S. Plimpton) –Evaluating AZTEC linear solvers in NIMROD –Extends capabilities to non-symmetric/non-Hermitian systems TSTT Center (RPI) –Evaluating higher order finite elements by interfacing with SCOREC software –Initially using simplified 2D MHD problem, but similar in structure to M3D –Discussions regarding spectral elements ADPEC Center (LBL) –Incorporation of MHD into Chambo Parallel AMR framework –Initial application to reconnection problem –R. Samtaney to report on progress

ADDITION OF SMALL NON-IDEAL PHYSICS CAN LEAD TO STRONG STOCHASTICITY OF MAGNETIC FIELD LINES Simulation with small but finite resistivity Ideal mode yields stochastic field lines in late nonlinear stage Implications for degraded/loss of confinement t = 1.99 X sec.t = X sec. t = X sec. t = 2.2 X sec.

Advantages of AMR Example: 2D MHD Efficiency of AMR High effective resolution Level# grids# grid points Grid points in adaptive simulation: Grid points in non-adaptive simulation: Ratio0.02 log

Scaling on a model reconnection problem

MHD CODES HAVE A WIDE RANGE OF CROSS- CUTTING APPLICATIONS Cellular detonation Compressed turbulence Helium burning on neutron stars Richtmyer-Meshkov instability Nova outbursts on white dwarfs Rayleigh-Taylor instability Flame-vortex interactions Wave breaking on white dwarfs Orzag/Tang MHD vortex Type Ia Supernova Intracluster interactions Magnetic Rayleigh-Taylor