A publication of the Advanced Simulation & Computing Division, NA-121.2, NNSA Defense Programs
June 2008
NA-ASC-500-08—Issue 7
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Progress in HEDP Code Consolidation
In connection with the ASC Integrated Codes strategy, and the associated code consolidation efforts to eliminate unnecessary duplication of capability, Sandia and Lawrence Livermore are transferring selected magneto-hydrodynamics (MHD) capabilities developed and implemented in Sandia’s ALEGRA code into Lawrence Livermore’s high energy density physics (HEDP) codes. An early success was achieved in this collaboration through implementation of a package from ALEGRA for ideal MHD modeling in the Lawrence Livermore KULL code.
The new capability allows users to initialize arbitrary magnetic fields for subsequent MHD simulations. The Intrepid package in the Sandia Trilinos library is used to reconstruct the magnetic field, which is then used to calculate magnetic stresses for the hydrodynamics package.
Several test problems have been created in the KULL test suite to verify each part of the code created so far, including tests for serial and parallel consistency, initialization, Intrepid tests, and some simple steady-state ideal MHD problems. The new MHD capability has been used to calculate the results of a Ryu-Jones test problem in which density, magnetic field, and pressure discontinuities generate various shock and rarefaction waves.
The KULL 2D and 3D solutions for the test problem compare well with both ALEGRA and analytic solutions. The simulations are the first 2D ideal MHD calculations ever done in KULL.
The final state of a Grad-Shafranov steady state solution in 2D-XY. The color background corresponds to the magnetic pressure. The arrows represent the magnetic force on the nodes, using a new discretization. The black contour lines are gas pressure contours. You can see that the arrows are normal to the contours, and that the hydro and mag forces balance each other.
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