A comparative study of the commercial CFD codes: ANSYS Fluent and STAR-CCM+ to simulate nuclear fuel bundles

This paper presents an overview of the capability of two commercial computational fluid dynamics (CFD) codes, ANSYS Fluent and STAR-CCM+, for simulating flow and heat transfer in nuclear fuel (or rod) bundles with spacers. Fundamental aspects of the codes, turbulence models, and meshing strategies for rod bundle flows were discussed along with an in-depth review of selected studies that simulated rod bundles. A sensitivity study on turbulence models and code-to code comparison were performed by simulating 5-by-5 rod bundles with split spacer. The experimental trend of the axial velocity distribution downstream of the spacer was well predicted by both codes; the solutions are comparable with only minor differences that are attributed to differences in mesh topologies between the codes. Moreover, the suitability of STAR-CCM+ for simulating rod bundles in supercritical flow conditions was assessed by simulating a seven-rod bundle experiment with honey-comb spacers. The experimental trends of temperature variation along the length of the bundle were well predicted, thus demonstrating the potential of the code for modeling advanced reactor concepts with supercritical water as coolant. (author)