Development of Petra-M Framework: toward OS integrated FEM analysis

Progress in the Petra-M framework development is presented. Petra-M was originally built to solve the RF wave propagation problem. It uses the MFEM finite element library, and has been used for the variety of cold plasma wave simulations. Recent modeling needs motivated to extend Petra-M in order to allow for performing more complicated multi-physics type simulations. Such needs include integrating the RF rectified potential model, estimating the density modulation due to the Ponderomotive forces in front of antenna, investigating the scattering of RF wave due to the turbulence, and solving an electro-magnetic-thermal coupled problem in time domain. Petra-M now supports an arbitrary number of finite element space discrete variables defined over a part of input geometry, and a user-friendly interface allows for defining a coupling PDE system using MFEM Linear/BilinearForm integrators. A custom operator and preconditioner can be defined using Python decorator. In RF SciDAC4, these new features are used to integrate the RF sheath and the turbulence predicted by the BOUT++ code to SOL wave simulations. We discuss how to use Petra-M to prepare MFEM simulations using the variety of existing models.