Effect of a passive disturbance on the flow structure and heat transfer in the separation region behind a backward-facing step

The article presents the results of a numerical study of a separated, turbulent flow and heat transfer in a channel with a sudden expansion under the effect of a passive disturbance generated by a rib-vortex generator. The rib height and its position upstream of the backward-facing step were varied over a wide range. The simulation results demonstrated that the vortex generator exerted a strong effect on the turbulent energy field and the friction factor. Under these conditions, the heat-transfer coefficient changes only slightly, which indicates that the heat transfer has a very low sensitivity to the disturbances generated by the rib. The causes of this behavior of dynamic and thermal characteristics are discussed. The presented comparison of the predictions with the experimental data confirms their qualitative agreement.