Wall-resolved Large Eddy Simulation in grid-free 5 × 5 rod bundle of MATiS-H experiment

In the present paper the WALE model has been implemented in OpenFOAM code and applied for Large Eddy Simulation (LES) of two wall-bounded turbulent flow cases at moderately high Reynolds numbers, i.e. Re=O(104). Firstly, the LES using the WALE model is verified against the direct numerical simulation (DNS) of the turbulent channel flow at Reτ = 1020. An appropriate mesh discretization for a given numerical method is determined and the underresolution effects on first and second order moments of velocity are investigated. Then, the obtained best practices are used for accurate wall-resolved LES of a turbulent flow in the 5 × 5 rod fuel bundle. The velocities and fluctuations are compared with Laser Doppler Velocimetry measurements of the MATiS-H experiment, which was performed in 2011 at KAERI, South Korea. Experiments and simulations are compared in the bare fuel bundle section without spacer grids. LES using WALE model is found as a pretty accurate tool for simulations of the flow through the rod bundle, if sufficiently fine mesh is applied. Mean velocity profiles are predicted with a remarkable accuracy, while the second-order statistics exhibit slightly larger discrepancies.