This project focuses on the development of scalable, parallel, numerical models for the simulation of space plasmas and the dynamics of the Earth's magnetosphere, based on discrete event simulation (DES). Phenomena such as the interaction of the solar wind with the magnetosphere are large-scale problems that contain regions where smaller-scale dynamics dominates. The location and scale of these sub-regions evolve in time and the sub-regions themselves are characterized by dominant physical balances different to those controlling the larger-scale dynamics. Examples of regimes present in the problem of describing the interaction of the solar wind with the Earth's magnetosphere include ones controlled by electron kinetics, by ion physics, and by magnetohydrodynamics. Full particle simulation of such a problem is impractical because of the amount of computing resources that would be required. The investigators will develop DES methods with situation-dependent physics, suitable for space physics problems, and then develop the algorithms required to execute these efficiently on massively parallel computer systems. This will involve research into the stability and accuracy of these methods, the extension of existing one-dimensional prototypes to 3D, optimization for parallel environments, ways of connecting regions in which different physical balances predominate, adaptive algorithms, and the evaluation of different approaches to mesh design. Event-based simulations are inherently dynamic in ways that make compile-time optimization difficult; the reverse-execution approach proposed further complicates the task of automatic optimization. The project will include research on compiler technology to improve the automatic optimization of event-based codes and the development of libraries of optimized reversible primitives. This type of research may lead to improvements in the ability to model space weather with the potential for significant impacts in the field of satellite communications. The modeling techniques to be developed might be useful in other areas of science and engineering where simulations of multi-scale, multi-physics regimes are required. The project includes research training opportunities for a number of graduate students.
