Abstract Details
Abstracts
Author: Ian Abel
Requested Type: Poster
Submitted: 2025-03-14 14:26:28
Co-authors: N. Mandell, P. Kim, D. Reynolds
Contact Info:
University of Maryland, College Park
8279 Paint Branch Drive
College Park, MD 20742
United States
Abstract Text:
Efficient modelling of gyrokinetic turbulence continues to be a key component of design activities for current and future fusion plasmas. The GX gyrokinetic code has recently released version 1.0 including several key algorithmic improvements which we describe here.
GX now includes a full flow-shear implementation, benchmarked against other gyrokinetic codes, while maintaining good efficiency.
Runge-Kutta time-stepping methods that permit a split between Implicit and Explicit components of the time-advance operator have been implemented. Implicit implementations of parallel dynamics as well as other linear terms in the gyrokinetic equation enable selecting larger timesteps for a wide range of problems. In particular, these methods permit faster electrostatic ion-scale simulations while retaining fully kinetic electrons.
Advanced adaptive time-stepping including new embeddings for Low-storage Runge-Kutta methods have been implemented in GX through coupling to the SUNDIALS library. These algorithms simplify achieving peak performance without the user carefully selecting the correct timestep. We demonstrate on several test problems that the embeddings, coupled to an adjustable error metric, helps select an efficient timestep.
Finally, GX now has a full HIP implementation. This enables GX to run on leadership facilities like Frontier (OLCF) and the new Japanese supercomputer being deployed at NIFS this year. We demonstrate good weak scaling on Frontier for typical workloads.
Characterization: 4.0
Comments: