Authors

Abstract

At the beginning of the last decade, Petascale supercomputers (i.e., computers capable of morethan 1 petaFLOP) emerged. Now, at the dawn of exascale supercomputing, we provide a review of recentlandmark simulations of portions of reactor components with turbulence-resolving techniques that this computational power has made possible. In fact, these simulations have provided invaluable insight into flowdynamics, which is difficult or often impossible to obtain with experiments alone. We focus on simulationsperformed with the spectral element method, as this method has emerged as a powerful tool to deliver massivelyparallel calculations at high fidelity by using large eddy simulation or direct numerical simulation. We also limitthis paper to constant-property incompressible flow of a Newtonian fluid in the absence of other body orexternal forces, although the method is by no means limited to this class of flows. We briefly review thefundamentals of the method and the reasons it is compelling for the simulation of nuclear engineering flows. Wereview in detail a series of Petascale simulations, including the simulations of helical coil steam generators, fuelassemblies, and pebble beds. Even with Petascale computing, however, limitations for nuclear modeling andsimulation tools remain. In particular, the size and scope of turbulence-resolving simulations are still limited bycomputing power and resolution requirements, which scale with the Reynolds number. In the final part of thispaper, we discuss the future of the field, including recent advancements in emerging architectures such as GPUbased supercomputers, which are expected to power the next generation of high-performance computers.