Gordon Bell finalist team pushes scale of rocket simulation on El Capitan

Summary

Researchers used Lawrence Livermore National Laboratory’s (LLNL) exascale supercomputer El Capitan to perform the largest fluid dynamics simulation ever — surpassing one quadrillion degrees of freedom in a single computational fluid dynamics (CFD) problem. The team focused the effort on rocket–rocket plume interactions. El Capitan is funded by the National Nuclear Security Administration’s (NNSA) Advanced Simulation and Computing (ASC) program. The work — in part performed prior to the transition of the world’s most powerful supercomputer to classified operations earlier this year — is led by researchers from Georgia Tech and supported by partners at AMD, NVIDIA, HPE, Oak Ridge National Laboratory (ORNL) and New York University’s (NYU) Courant Institute. The paper is a finalist for the 2025 ACM Gordon Bell Prize, the highest honor in high-performance computing. This year’s winner — selected from a small handful of finalists — will be announced at the International Conference for High Performance Computing, Networking, Storage, and Analysis (SC25) in St. Louis on Nov. 20. To tackle the extreme challenge of simulating the turbulent exhaust flow generated by many rocket engines firing simultaneously, the team’s approach combined a newly proposed shock-regularization technique called Information Geometric Regularization (IGR), invented and implemented by professors Spencer Bryngelson of Georgia Tech, Florian Schäfer of NYU Courant and Ruijia Cao (now a Cornell Ph.D. student). Using all 11,136 nodes and more than 44,500 AMD Instinct MI300A Accelerated Processing Units (APUs) on El Capitan, the team achieved better than 500 trillion grid points, or 500 quadrillion degrees of freedom. They further extended this to ORNL’s Frontier, surpassing one quadrillion degrees of freedom. The simulations were conducted with MFC, a permissively licensed open-source code maintained by Bryngelson’s group. With these simulations, they represented the full exhaust dynamics of a complex con...