CFD analysis of convective heat transfer at the surfaces of a cube immersed in a turbulent boundary layer

Steady Reynolds-Averaged Navier–Stokes (RANS) CFD is used to evaluate the forced convective heat transfer at the surfaces of a cube immersed in a turbulent boundary layer, for applications in atmospheric boundary layer (ABL) wind flow around surface-mounted obstacles such as buildings. Two specific configurations are analysed. First, a cube placed in turbulent channel flow at a Reynolds number of 4.6 × 103 is considered to validate the numerical predictions by comparison with wind-tunnel measurements. The results obtained with low-Reynolds number modelling (LRNM) show a satisfactory agreement with the experimental data for the windward surface. Secondly, a cube exposed to high-Reynolds number ABL flow is considered. The heat transfer in the boundary layer is analysed in detail. The dimensionless parameter y∗, which takes into account turbulence, is found to be more appropriate for evaluating heat transfer than the commonly used y+ value. Standard wall functions, which are frequently used for high-Reynolds number flows, overestimate the convective heat transfer coefficient (CHTC) significantly (±50%) compared to LRNM. The distribution of the CHTC–U10 correlation over the windward surface is reported for Reynolds numbers of 3.5 × 104 to 3.5 × 106 based on the cube height and U10, where U10 is the wind speed in the undisturbed flow at a height of 10 m.