A numerical study of turbulent upward flow of super critical water in a 2X2 rod bundle with non-uniform heating

This work is part of a benchmarking excise organized by IAEA CRP in SCWR thermalhydraulics aimed at improving the understanding and prediction accuracy of the thermalhydraulic phenomena relevant to SCWRs. An experiment carried out using a 2×2 SCWR bundle at University of Wisconsin-Madison was modelled using an open-source CFD code (Code_Saturne). The k-ω SST model was employed to account for the buoyancy-aided turbulent flow in the fuel channel. Significant heat transfer deterioration was observed in the boundary layer, which is commonly expected to occur in buoyancy-aided flows. For comparison, simulations were also conducted using ANSYS FLUENT with similar model setups. (author)