Numerical simulation of forced convection over steps at low Prandtl number

Convective heat transfer in laminar conditions is investigated numerically for a Prandtl number Pr = 0.025, representative of liquid lead-bismuth eutectic (LBE). The geometry selected is a periodic channel with a set of backward and forward steps. Finite-volume simulations are carried out on structured orthogonal curvilinear grids, for ten values of the Reynolds number up to the transitional range. It is shown how flow can undergo separation and reattachment also at very low-Re. The influence of flow separation mechanisms on local and global heat transfer rates is discussed, also considering the effect of different thermal boundary conditions imposed at the channel walls.