Energy Exascale CFD Simulations with the Spectral Element Method

Development and application of the open-source GPU-based fluid-thermal simulation code, NekRS, is described. Time advancement is based on an efficient kth-order accurate time split formulation coupled with scalable iterative solvers. Spatial discretization is based on the high-order spectral element method (SEM), which allows fast, low-memory, matrix-free operator evaluation. Recent developments include support for nonconforming meshes using overset grids and GPU-based Lagrangian particle tracking. Results of large eddy simulations of atmospheric boundary layers for wind-energy applications and extensive nuclear energy applications are presented.