The Effects of Realistic Nuclear Kinetics, Dimensionality, and Resolution on Detonations in Low-Density Type Ia Supernovae Environments

Type Ia supernovae are most likely thermonuclear explosions of carbon/oxygen white dwarves in binary stellar systems. These events contribute to the chemical and dynamical evolution of their host galaxies and are essential to our understanding of the evolution of our universe through their use as cosmological distance indicators. Nearly all of the currently favored explosion scenarios for these supernovae involve detonations. However, modeling astrophysical detonations can be complicated by numerical effects related to grid resolution. In addition, the fidelity of the reaction network chosen to evolve the nuclear burning can alter the time and length scales over which the burning occurs. Multidimensional effects further complicate matters by introducing a complex cellular structure within the reaction zone. Here, we report on how these complications can affect the outcome of simulating such astrophysical detonations in the context of Type Ia supernovae

Application Porting and Optimization on GPU-Accelerated POWER Architectures

The POWER processor has re-emerged as a technology for supercomputer architectures. One major reason is the tight integration of processor and GPU accelerator through the NVLink technology. Two major sites in the US, ORNL and LLNL, deployed their pre-exascale systems based on this new architecture (Summit and Sierra, respectively).This tutorial gives an opportunity to obtain in-depth knowledge and experience with GPU-accelerated POWER nodes. It focuses on porting applications to a single node and covers the topics architecture, compilers, performance analysis and tuning, and multi-GPU programming. The tutorial includes an overview of the NVLink-based node architectures, lectures on first-hand experience in porting to this architecture, and exercises using tools to focus on performance