Flash-X, a composable and configurable software system for supernova simulations at extreme scales

Flash-X is a new multiphysics software system partially derived from

FLASH, a well recognized community code that has been in existence

from 2000. FLASH was designed only for bulk-synchronous

distributed-memory parallel model which makes it unsuitable for use on

newer platforms with accelerators. Flash-X has a fundamentally

redesigned architecture that uses abstractions and asynchronous

operations for portability across a variety of platforms, both with

and without accelerators. The design relies upon self-describing code

components that can be used to synthesize application instances. The

synthesis is done with a combination of assembly, code translation and

code generation. Accompanying tools for code translation and runtime

management are new and enable orchestration of computation and data

movement between distinct compute devices on a node.

In addition to the new architecture, Flash-X has newer and/or

higher-fidelity physics solvers for reactive magnetohydrodynamics,

nuclear burning, neutrino radiation transport, and other

microphysics. Flash-X was used to showcase the key performance

parameters of ExaStar a project under the Exascale Computing Project,

through a core-collapse supernova (CCSN) simulation on Frontier. This

poster describes the architecture and capabilities of Flash-X that are

relevant for various astrophysics applications.