NIMRODPast and Future Challenges

11/7/01


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Table of Contents

NIMRODPast and Future Challenges

Outline

NIMROD Project Created to Provide Tool for Fusion Community

NIMROD is a Multi-Institutional Team

NIMROD Solves the Extended MHD Equations

Computational Resistive MHD Provides Many Challenges

Adding Physics Restricts Computational Freedom

Time Step Limited With Explicit Methods

Temporal Stiffness Solved By Using Semi-Implicit Method

Spatial Discretization Uses Finite-Elements in Poloidal Plane

Toroidal Direction Uses Fourier Decomposition

The NIMROD Project Has Made Significant Progress

Shot #87009 Sees Instability Driven Through Threshold

Observed Growth is Faster Than Exponential

Model Experiment With Fixed Boundary Equilibria

NIMROD Qualitatively Agrees with Theory

Anisotropic Pressure Diffusion About Island Degrades Performance

Higher-Order Elements Allow Realistic Values of c||/ cperp

Higher-Order Elements Allow NTM Simulations

Resistive Wall Implemented for Simple Geometry

NIMROD Can Include Vacuum Regions Beyond Separatrix

With Vacuum, Normal Magnetic Field Shows 2/1 Dominance

Numerical Difficulties Still Exist For Equilibrium Shear Flow

Longer Term Projects Will Greatly Enhance Capabilities

Conclusions

Conclusions (cont)

Author: Scott Kruger

Email: krugers@saic.com

Home Page: http://nimrodteam.org