Objective: To develop a fluid dynamics code which incorporates the effects of magnetic and radiation fields for massively parallel supercomputers and apply it to the study of the dynamics of astrophysical plasmas.
Approach: Standard finite-difference methods are used to evolve the equations of fluid dynamics. Special purpose algorithms developed by the PI are used to evolve the magnetic and radiation fields. The code is written in Fortran using a data parallel paradigm.
Accomplishments: Fully three-dimensional hydrodynamic algorithms including the effects of magnetic fields have been implemented on a variety of massively parallel supercomputers, including the Connection Machine 2 (CM-2), CM-5, and MasPar-2. Performance on these machines varies from 2-20 times faster than on one Cray YMP processor. The code is now being used to study the dynamics of magnetized accretion disks. The accompanying figure shows the turbulence which results in a three-dimensional section of a weakly magnetized accretion disk from the development of magnetic instabilities in the flow. The magnetic field lines (yellow) have become highly tangled, and the density (colors) shows large amplitude fluctuations characteristic of turbulence in the midplane of the disk.
Significance: Many astrophysical systems behave as fluids, thus a theoretical description of their dynamics is given by solutions of the equations of fluid dynamics. However, astrophysical plasmas are complex because they are affected by a variety of physical phenomena, such as magnetic fields and radiation fields from nearby stars. By implementing numerical algorithms for magnetic fluids on massivley parallel machines, the largest and most detailed numerical simulations of the dynamics of astrophyscial plasmas in a variety of contexts will be possible.
Status/Plans: Year 2 milestones have been reached: the hydrodynamic algorithms including the effects of a magnetic field have been implemented on a variety of massively parallel machines, and significant applications have been made. Future plans include implementing the radiation hydrodynamic algorithms on parallel machines, and porting the existing code to message passing architectures.
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