Direct numerical simulation of turbulent flows in VVER-440 fuel rod bundles

The paper presents results of the DINUS code verification against data from experiments conducted at a full-size test facility in Finland. The DINUS code is intended for direct numerical simulation of thermal-hydraulic processes in reactor fuel rod bundles. The experiments studied hydrodynamic processes in the VVER-440 fuel rod bundle at the Loviisa NPP and were carried out for the Reynolds number of 50000. A comparison is given for calculated and experiment data on the axial velocity and flow turbulence intensity distributions at the rod bundle cross sections at different distances from the spacer grid. The DINUS code was used to analyze the effect of the spacer grid on the intensity of inter-subchannel turbulent mixing and convective transfer.