Core Infrastructure Upgrades to the NIMROD Codebase*

In order to increase functionality of the NIMROD code, we are refactoring data structures and interpolation routines using object-oriented features introduced in Fortran 2003/2008. This change is motivated by physics-oriented objectives. First, the element representation needs another dimension for the continuum kinetic model to take advantage of sparsity in the pitch-angle coordinate. Second, we are interested in flexibility with regard to the mesh representation and the finite-element function spaces. We have created new abstract interfaces for the concepts of mesh block, finite-element field, and for the linear algebra data structures. Currently, mesh blocks are in practice limited to regions of structured quadrilaterals. Greater use of object-oriented programming will facilitate implementation of unstructured triangle and quadrilateral meshes. We currently represent our quadrilateral finite element fields as C₀ functions. In order to investigate novel methods for solving Hall-MHD, we are also interested in being able to approximate other function spaces such as H(curl). Here we present the current status of these updates and provide example code changes.