Simulation of turbulent flow in MATIS-H rod bundle with split-type mixing vanes

Turbulent flow simulations of 5 × 5 rod bundle with the split-type mixing grid are presented. The simulations were performed by the Jožef Stefan Institute (JSI) in the frame of its participation in the OECD/NEA CFD Benchmark exercise. The experimental data from the MATIS-H benchmark experiment located at the Korean Atomic Energy Research Institute (KAERI) were used for posteriori comparison with simulation results. To predict the flow between the rods and mixing vanes, a complex, fully hexagonal flow-oriented mesh was constructed, taking into account the geometry of mixing vanes. High resolution numerical methods and a scale-resolving turbulence model was used in ANSYS CFX simulation. Time-averaged velocity profiles, profiles of velocity fluctuations and integral velocity circulation at the specified downstream locations show good agreement with experimental data. In addition, the simulated flow patterns over the entire rod bundle cross-section are presented and discussed.