Software Development

During FY02, we completed the following software development activities.

• We completed an initial implementation of a general package for the unsplit high-order Godunov methods for hyperbolic conservation laws, designed in FY01. This driver implements the algorithm for a large class of systems, requiring the user to provide only a small amount of physics-dependent information. We also completed the implementation of stand-alone AMR variable-coefficient scalar and tensor solvers for elliptic and parabolic equations, and began the initial investigation of the coupling of those solvers to the Hypre package being developed in the TOPS project. The hyperbolic, elliptic and parabolic solvers described here are the basis for the AMR MHD code developed in FY02.

• We completed an initial implementation of the layered AMR architecture for embedded boundary applications. These include the development of system solvers required for the magnetic fusion and viscous gas jet applications, as well as the extension to cylindrical coordinates of the embedded boundary software required to represent the plasma boundary in a tokomak. We also completed an initial interface between the Cart3D grid generator and our embedded boundary classes.

• We completed the inital development of the layered AMR architecture for particle-in-cell codes. The fundamental data type for particle-in-cell methods is a multidimensional rectangular array, each element of which is a set of particles. We developed a Layer 1 capability corresponding to such data defined on unions of rectangles, with the rectangles distributed over processors. We also developed a version of the Layer 2 tools for interpolating between particles and AMR grids the generalize the classical PIC operators for nodal-point discretizations of Poisson's equation. These classes, along with a nodal-point AMR solver for Poisson's equation, form the basis for the AMR-PIC capability developed for RF accelerator modeling in FY02.

• We completed the initial design and implementation of interoperability tools for AMR calculations. These include C wrappers for the various solvers used to implement the AMR-PIC code for accelerator modeling, and the interface to AMR I/O. We also initiated a collaboration among the various block-structured AMR activities in SciDAC, under the auspices of the CCA effort, to develop a common set of adaptors and other components that will facilitate interoperability among various AMR software components.