Visualizing the world's largest turbulence simulation

We describe a novel, scalable approach for scientific visualization in HPC environments, based on the ray tracing engine Intel® OSPRay associated with VisIt. Part of the software stack of the Leibniz Supercomputing Centre, this method has been applied to the visualization of the largest simulations of interstellar turbulence ever performed, produced on SuperMUC-NG. The hybrid (MPI + Threading Building Blocks) parallelization of OSPRay and VisIt allows efficient scaling up to about 150 thousand cores, making it possible to visualize the data at the full, unprecedented resolution of 10048³ grid elements (about 23 TB per snapshot). Besides presenting the method, its HPC context and future developments, we describe the implications of our visualization in the considered science case: our work brilliantly showcases the stretching-and-folding mechanisms through which astrophysical processes drive turbulence and amplify the magnetic field in the interstellar gas, and how the first structures, the seeds of newborn stars are shaped by this process. We finally observe the similarities between ray tracing and other HPC numerical techniques used in astrophysics, anticipating increasing convergences in the near future.