A HYDRA UQ Workflow for NIF Ignition Experiments

We describe the use of our in-transit workflow infrastructure to run an ensemble of HYDRA [1] [2] Inertial Confinement Fusion (ICF) simulations in support of experiments conducted using the National Ignition Facility (NIF) laser. We discuss how our approach can be used to gain deeper insight into NIF experiments. We ran over 60,000 2D HYDRA simulations and generated over a billion synthetic x-ray images during 8 weeks on the Trinity Cray XC40 system. These represent a majority of all 2D simulations run during HYDRA's 20 year history. We implemented a producer-consumer in-transit framework to minimize the amount of disk space used to generate synthetic x-ray images. We describe our infrastructure and approach, and explore the scaling and performance issues we ran into. Our goal is to help others plan for large ensemble simulations and discuss changes to system software that would make it easier to run large ensembles.