Space and energy-based turbulent scale-resolving simulations of flow in a 5 × 5 nuclear reactor core fuel assembly with a spacer grid

The partially averaged Navier-Stokes turbulence model, which is a bridging model between the Reynolds averaged Navier-Stokes model and direct numerical simulation, is capable of directly resolving the turbulent scales of interest by filtering the Navier-Stokes equation using turbulent kinetic energy and dissipation based filters. In this study, comparison is made between the partially averaged Navier-Stokes and large eddy simulation models, with emphasis on the mean flow characteristics and spatio-temporal turbulent flow structures. The results show that the partially averaged Navier-Stokes modeling produces results comparable to those of large eddy simulation when the appropriate cut-off energy filter is chosen. The test case involves simulating flows in a 5 × 5 fuel rod bundle configuration with a spacer grid at a Reynolds number of 14,000. The simulation results are compared with particle image velocimetry data obtained from the scientific literature.