Turbulence models evaluation for heat transfer simulation in tight lattice fuel bundles

A comparative evaluation of different turbulence models is presented in this work, to select which one could be adopted for the evaluation of thermo-hydraulic performances of tight lattice fuel bundles. Each model is briefly introduced and discussed, including linear, quadratic and cubic version of the k- ε model, the k-ω model, and the SST model by Menter. Capabilities of the various turbulence closures are evaluated on a benchmark describing a heated bundle, containing four rods arranged in one row, with sodium cooling. Coolant temperatures from the experiment are compared with the computed values, in a region between the rods, and near the channel periphery. The results show that the linear k-ε, k-ω and SST models obtain a very close agreement with each other, but are not capable of correctly predicting the temperature field, due to their inability to account for anisotropy. Quadratic and cubic models instead are capable of producing close agreement with the experimental data, being able to account, in some extent, for the anisotropy